Chris is an absolute legend in this space and I’m so glad he’s bringing this up. I feel like he might actually have pull here and start good discussions that might have actual solutions.
dwheeler · 6h ago
HTML was historically an application of SGML, and SGML could do includes. You could define a new "entity", and if you created a "system" entity, you could refer to it later and have it substituted in.
<!DOCTYPE html example [
<!ENTITY myheader SYSTEM "myheader.html">
]>
....
&myheader;
SGML is complex, so various efforts were made to simplify HTML, and that's one of the capabilities that was dropped along the way.
int_19h · 4h ago
We also had a brief detour into XML with XHTML, and XML has XInclude, although it's not a required feature.
echelon · 21m ago
It's too bad we didn't go down the XHTML/semantic web route twenty years ago.
Strict documents, reusable types, microformats, etc. would have put search into the hands of the masses rather than kept it in Google's unique domain.
The web would have been more composible and P2P. We'd have been able to slurp first class article content, comments, contact details, factual information, addresses, etc., and built a wealth of tooling.
Google / WhatWG wanted easy to author pages (~="sloppy markup, nonstandard docs") because nobody else could "organize the web" like them if it was disorganized by default.
Once the late 2010's came to pass, Google's need for the web started to wane. They directly embed lifted facts into the search results, tried to push AMP to keep us from going to websites, etc.
Google's decisions and technologies have been designed to keep us in their funnel. Web tech has been nudged and mutated to accomplish that. It's especially easy to see when the tides change.
j45 · 2h ago
Neat reference, going to look into that.
The <object> tag appears to include/embed other html pages.
This was the rabbit hole that I started down in the late 90s and still haven’t come out of. I was the webmaster of the Analog Science Fiction website and I was building tons of static pages, each with the same header and side bar. It drove me nuts. So I did some research and found out about Apache server side includes. Woo hoo! Keeping it DRY (before I knew DRY was a thing).
Yeah, we’ve been solving this over and over in different ways. For those saying that iframes are good enough, they’re not. Iframes don’t expand to fit content. And server side solutions require a server. Why not have a simple client side method for this? I think it’s a valid question. Now that we’re fixing a lot of the irritation in web development, it seems worth considering.
A small 10KB lib that augments HTML with the essential good stuff (like dynamic imports of static HTML)
HumanOstrich · 54m ago
Seems like overkill to bring in a framework just for inlining some static html. If that's all you're doing, a self-replacing script tag is neat:
<script>
function includeHTML(url) {
const s = document.currentScript
fetch(url).then(r => r.text()).then(h => {
s.insertAdjacentHTML('beforebegin', h)
s.remove()
})
}
</script>
...
<script>
includeHTML('/footer.html')
</script>
The `script` element is replaced with the html from `/footer.html`.
EvanAnderson · 50m ago
Server-side includes FTW! When a buddy and I started making "web stuff" back in the mid-90s the idea of DRY also just made sense to us.
My dialup ISP back then didn't disable using .htaccess files in the web space they provided to end users. That meant I could turn on server-side includes! Later I figured out how to enable CGI. (I even went so far as to code rudimentary webshells in Perl just so I could explore the webserver box...)
I used the seamless attribute extensively in the past, it still doesn't work the way GP intended, which is to fit in the layout flow, for example to take the full width provided by the parent, or automatically resize the height (the pain of years of my career)
It worked rather like a reverse shadow DOM, allowing CSS from the parent document to leak into the child, removing borders and other visual chrome that would make it distinguishable from the host, except you still had to use fixed CSS layouts and resize it with JS.
codr7 · 8h ago
The optimal solution would be using a template engine to generate static documents.
JadeNB · 7h ago
> The optimal solution would be using a template engine to generate static documents.
This helps the creator, but not the consumer, right? That is, if I visit 100 of your static documents created with a template engine, then I'll still be downloading some identical content 100 times.
codr7 · 3h ago
True for any server side solution, yes.
On the other hand it means less work for the client, which is a pretty big deal on mobile.
giantrobot · 6h ago
XSLT solved this problem. But it had poor tool support (DreamWeaver etc) and a bunch of anti-XML sentiment I assume as blowback from capital-E Enterprise stacks going insane with XML for everything.
XSLT did exactly what HTML includes could do and more. The user agent could cache stylesheets or if it wanted override a linked stylesheet (like with CSS) and transform the raw data any way it wanted.
px1999 · 3h ago
The Umbraco CMS was amazing during the time that it used and supported XSLT.
While it evaluated the xslt serverside it was a really neat and simple approach.
keeganpoppen · 7h ago
macros!
econ · 12h ago
You can message the page dimensions to the parent. To do it x domain you can load the same url into the parent with the height in the #location hash. It won't refresh that way.
dimal · 12h ago
I know it’s possible to work around it, but that’s not the point. This is such a common use case that it seems worthwhile to pave the cowpath. We’ve paved a lot of cowpaths that are far less trodden than this one. This is practically a cow superhighway.
We’ve built an industry around solving this problem. What if, for some basic web publishing use cases, we could replace a complex web framework with one new tag?
> XHTML 2 takes a completely different approach, by taking the premise that all images have a long description and treating the image and the text as equivalents. In XHTML 2 any element may have a @src attribute, which specifies a resource (such as an image) to load instead of the element.
fooker · 5h ago
> Why not have a simple client side method for this?
Like writing a line of js?
sbarre · 4h ago
A line of JS that has to run through the Javascript interpreter in your browser rather than a simple I/O operation?
If internally this gets optimized to a simple I/O operation (which it should) then why add the JS indirection in the first place?
atoav · 11h ago
I mean in 1996s netscape you could do this (I run the server for a website that still uses this):
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">
<html>
<frameset cols="1000, *">
<frame src="FRAMESET_navigation.html" name="navigation">
<frame src="FRAMESET_home.html" name="in">
</frameset>
</html>
The thing that always bugged me about frames is that they are too clever. I don't want to reload only the frame html when I rightclick and reload. Sure the idea was to cache those separately, but come on — frames and caching are meant to solve two different problems and by munching them together they somewhat sucked at solving either.
To me includes for HTML should work in the dumbest way possible. And that means: Take the text from the include and paste it where the include was and give the browser the resulting text.
If you want to cache a nav section separately because it appears the same on every page lets add a cache attribute that solves the problem independently:
To tell the browser it should load the inner html or the src of that element from cache if it has it.
Now you could convince me thst the include should allow for more, but it being dumb is a feature not a bug.
api · 8h ago
The web seems like it was deliberately designed to make any form of composability impossible. It’s one of the worst things about it as a platform.
I’m sure some purist argument has driven this somewhere.
giantrobot · 6h ago
I look back longingly at the promise of XML services in the early days of Web 2.0. Before the term just meant JavaScript everywhere.
All sorts of data could be linked together to display or remix by user agents.
luotuoshangdui · 11h ago
HTML is a markup language, not a programming language. It's like asking why Markdown can't handle includes. Some Markdown editors support them (just like some server-side tools do for HTML), but not all.
franga2000 · 10h ago
Including another document is much closer to a markup operation than a programming operation. We already include styles, scripts, images, videos, fonts...why not document fragments?
Markdown can't do most of those, so it makes more sense why it doesn't have includes, but I'd still argue it definitely should. I generally dislike LaTeX, but about the only thing I liked about it when writing my thesis was that I could have each chapter in its own file and just include all of them in the main file.
dimal · 10h ago
This isn’t programming. It’s transclusion[0]. Essentially, iframes and images are already forms of transclusion, so why not transclude html and have the iframe expand to fit the content?
As I wrote that, I realized there could be cumulative layout shift, so that’s an argument against. To avoid that, the browser would have to download all transcluded content before rendering. In the past, this would have been a dealbreaker, but maybe it’s more feasible now with http multiplexing.
With Early Hints (HTTP code 103), it seems especially feasible. You can start downloading the included content one round-trip after the first byte is sent.
lenkite · 8h ago
Well, asciidoc - a markup language supports includes, so the "markup languages" analogy doesn't hold.
I'm not defending it, because when I started web development this was one of the first problems I ran into as well -- how the heck do you include a common header.
But the original concept of HTML was standalone documents, not websites with reusable components like headers and footers and navbars.
That being said, I still don't understand why then the frames monstrosity was invented, rather than a basic include. To save on bandwidth or something?
int_19h · 3h ago
The original concept of HTML was as an SGML subset, and SGML had this functionality, precisely because it's very handy for document authoring to be able to share common snippets.
giantrobot · 6h ago
Frames were widely abused by early web apps to do dynamic interfaces before XHR was invented/widely supported. The "app" had a bunch of sub-frames with all the links and forms carefully pointing to different frames in the frameset.
A link in a sidebar frame would open a link in the "editor" frame which loaded a page with a normal HTML form. Submitting the form reloaded it in that same frame. Often the form would have multiple submit buttons, one to save edits in progress and another to submit the completed form and move to the next step. The current app state was maintained server side and validation was often handled there save for some basic formatting client side JavaScript could handle.
This setup allowed even the most primitive frame-supporting browsers to use CRUD web apps. IIRC early web frameworks like WebObjects leaned into that model of web app.
crazygringo · 4h ago
Oh my goodness, yes you're right, I'd forgotten entirely about those.
They were horrible -- you'd hit the back button and only one of the frames would go back and then the app would be in an inconsistent state... it was a mess!
giantrobot · 3h ago
You needed to hit the reset button (and hoped it worked) and never the back button! Yes, I suffered through early SAP web apps built entirely with frames and HTML forms. It was terrible.
I don't love JavaScript monstrosities but XHR and dynamic HTML were a vast improvement over HTML forms and frame/iframe abuse.
cr125rider · 4m ago
To be fair, modern SAP web apps are also terrible.
mattl · 6h ago
A lot of early HTML was about taking the output of a different system such as a mainframe and putting that output into HTML.
Lots of gateways between systems.
paulddraper · 10h ago
That’s the Hyper part of HTML, and what makes it special.
It’s made to pull in external resources (as opposed to other document formats like PDF).
Scripts, stylesheets, images, objects, favicons, etc. HTML is thematically similar.
ummonk · 8h ago
No, HTML is fundamentally different because (for a static site without any JS dom manipulation) it has all the semantic content, while stylesheets, images, objects, etc. are just about presentation.
paulddraper · 3h ago
Images are content. Videos are content. Objects/iframes are content.
The only one that is presentational is stylesheets.
hnick · 2h ago
Which (as I'm sure you know), also literally has 'content' :)
Markdown doesn't have this common HTML pattern of wanting to include a header/footer in all pages of a site.
throwup238 · 11h ago
The feature proposal was called HTML Imports [1], created as part of the Web Components effort.
> HTML Imports are a way to include and reuse HTML documents in other HTML documents
There were plans for <template> tag support and everything.
If I remember correctly, Google implemented the proposed spec in Blink but everyone else balked for various reasons. Mozilla was concerned with the complexity of the implementation and its security implications, as well as the overlap with ES6 modules. Without vendor support, the proposal was officially discontinued.
That matches with the comment [1] on the article, citing insufficient demand, no vendor enthusiasm, etc.
The thing is that all those are non-reasons that don't really explain anything: Low demand is hard to believe if this feature is requested for 20 years straight and there are all kinds of shim implementations using scripts, backend engines, etc. (And low demand didn't stop other features that the vendors were interested in for their own reasons)
Vendor refusal also doesn't explain why they refused it, even to the point of rolling back implementations that already existed.
So I'd be interested to understand the "various reasons" in more detail.
"Security implications" also seem odd as you already are perfectly able to import HTML cross origin using script tags. Why is importing a script that does document.write() fine, but a HTML tag that does exactly the same thing hugely problematic?
(I understand the security concern that you wouldn't want to allow something like "<import src=google.com>" and get an instant clone of the Google homepage. But that issue seems trivially solvable with CORS.)
HTML Imports went in a similar direction but they do not do what the blog post is about. HTML should be imported and displayed in a specific place of the document. HTML Imports could not do this without JavaScript.
To be fair, it was pretty complicated. IIRC, using it required using Javascript to instantiate the template after importing it, rather than just having something like <include src="myinclude.html">.
paulddraper · 55m ago
Tbf, HTML Imports were significantly more complex than includes, which this article requests.
It was part of Project Xanadu, and originally considered to be an important feature of hypertext.
Notably, mediawiki uses transclusion extensively. It sometimes feels like the wiki is the truest form of hypertext.
jes5199 · 56m ago
Ward Cunningham (inventor of the Wiki) spent some time trying to invent a transclusion-first wiki, where everyone had their own wiki-space and used transclusion socially https://en.wikipedia.org/wiki/Federated_Wiki
it never quite took off
socalgal2 · 4h ago
There are all kind of issues with HTML include as others have pointed out
If main.html includes child/include1.html and child/include1.html has a link src="include2.html" then when the user clicks the link where does it go? If it goes to "include2.html", which by the name was meant to be included, then that page is going to be missing everything else. If it goes to main.html, how does it specify this time, use include2.html, not include1.html?
You could do the opposite, you can have article1.html, article2.html, article3.html etc, each include header.html, footer.html, navi.html. Ok, that works, but now you've make it so making a global change to the structure of your articles requires editing all articles. In other words, if you want to add comments.html to every article you have to edit all articles and you're back to wanting to generate pages from articles based on some template at which point you don't need the browser to support include.
I also suspect there would be other issues, like the header wants to know the title, or the footer wants a next/prev link, which now require some way to communicate this info between includes and you're basically back to generate the pages and include not being a solution
I think if you work though the issues you'll find an HTML include would be practically useless for most use cases.
int_19h · 3h ago
These are all solvable issues with fairly obvious solutions. For example:
> If main.html includes child/include1.html and child/include1.html has a link src="include2.html" then when the user clicks the link where does it go? If it goes to "include2.html", which by the name was meant to be included, then that page is going to be missing everything else. If it goes to main.html, how does it specify this time, use include2.html, not include1.html?
There are two distinct use cases here: snippet reuse and embeddable self-contained islands. But the latter is already handled by iframes (the behavior being your latter case). So we only need to do the former.
rchaud · 12h ago
"Includes" functionality is considered to be server-side, i.e. handled outside of the web browser. HTML is client-side, and really just a markup syntax, not a programming language.
As the article says, the problem is a solved one. The "includes" issue is how every web design student learns about PHP. In most CMSes, "includes" become "template partials" and are one of the first things explained in the documentation.
There really isn't any need to make includes available through just HTML. HTML is a presentation format and doesn't do anything interesting without CSS and JS anyway.
naasking · 11h ago
> "Includes" functionality is considered to be server-side, i.e. handled outside of the web browser. HTML is client-side, and really just a markup syntax, not a programming language.
That's not an argument that client-side includes shouldn't happen. In fact HTML already has worse versions of this via frames and iframes. A client-side equivalent of a server-side include fits naturally into what people do with HTML.
tgv · 10h ago
I think it feels off because an HTML file can include scripts, fonts, images, videos, styles, and probably a few other things. But not HTML. It can probably be coded with a custom element (<include src=.../>). I would be surprised if there wasn't a github repo with something similar.
c-smile · 1h ago
> "Includes" functionality is considered to be server-side
Exactly! Include makes perfect sense on server-side.
But client-side include means that the client should be able to modify original DOM at unknown moment of time. Options are
1. at HTML parse time (before even DOM is generated). This requires synchronous request to server for the inclusion. Not desirable.
2. after DOM creation: <include src=""> (or whatever) needs to appear in the DOM, chunk loaded asynchronously and then the <include> DOM element(sic!) needs to be replaced(or how?) by external fragment. This disables any existing DOM structure validation mechanism.
Having said that...
I've implemented <include> in my Sciter engine using strategy #1. It works there as HTML in Sciter usually comes from local app resources / file system where price of issuing additional "get chunk" request is negligible.
Well said this is many students' intro to PHP. Why not `<include src=header.html/>` though?
Some content is already loaded asynchronously such as images, content below the fold etc.
> HTML is really just a markup syntax, not a programming language
flamebait detected :) It's a declarative language, interpreted by each browser engine separately.
gyesxnuibh · 12h ago
What's the ML in HTML stand for? I think that's probably the crux of the argument. Are we gonna evolve it past its name?
Aloisius · 9h ago
If the issue is that "include" somehow makes it sound like it's not markup, the solution seems obvious. Just use the src attribute on other tags:
<html src="/some/page.html">, <div src="/some/div.html">, <span src="/some/span.html">, etc.
Or create a new tag that's a noun like fragment, page, document, subdoc or something.
Surely that's no less markup than svg, img, script, video, iframe, and what not.
No comments yet
int_19h · 3h ago
It stands for "markup language", and was inherited from SGML, which had includes. Strictly speaking, so did early HTML (since it was just an SGML subset), it's just that browsers didn't bother implementing it, for the most part. So it's not that it didn't evolve, but rather it devolved.
Nor is this something unique to SGML. XML is also a "markup language", yet XInclude is a thing.
cantSpellSober · 12h ago
That's why I joked about flamebait, it's hypertext though, aren't anchors essentially a goToURL() click handler in some ways? Template partials seem like a basic part of this system.
> considered to be server-side
Good point! Wouldn't fetching a template partial happen the same way (like fetching an image?)
mattl · 6h ago
> What's the ML in HTML stand for?
I always assumed it stood for my initials.
assimpleaspossi · 12h ago
Agree with what you said, however, HTML is a document description language and not a presentation format. CSS is for presentation (assuming you meant styling).
PaulDavisThe1st · 11h ago
They didn't mean styling.
HTML is a markup language that identifies the functional role of bits of text. In that sense, it is there to provide information about how to present the text, and is thus a presentation format.
It is also a document description language, because almost all document description languages are also a presentation format.
amadeuspagel · 10h ago
This argument applies just as much to CSS and JS. Why do they include "includes" when you can just bundle on the server?
adregan · 8h ago
For caching and sharing resources across the whole site, I suppose.
Linux-Fan · 12h ago
Isn't this what proper framesets (not iframes) were supposed to do a long time ago (HTML 4?). At least they autoexpanded just fine and the user could even adjust the size to their preference.
There was a lot of criticism for frames [1] but still they were successfully deployed for useful stuff like Java API documentation [2].
In my opinion the whole thing didn't stay mostly because of too little flexibility for designer: Framesets were probably well enough for useful information pages but didn't account for all the designers' needs with their bulky scrollbars and limited number of subspaces on the screen. Today it is too late to revive them because framesets as-is wouldn't probably work well on mobile...
Issue with frame set was way more fundamental: No deep linking, thus people coming via bookmarks or Google (or predecessor) were left on a page without navigation, which people then tried working around with JavaScript, which never gave it a good experience.
Linux-Fan · 12h ago
Nowdays it is sometimes the other way around: Pages are all JavaScript so no good experience in the first place. I have encountered difficulty trying to get a proper “link” to something multiple times. Also, given that Browsers love to reduce/hide the address bar I wonder if it is really still that important a feature.
Of course "back then" this was an important feature and one of the reasons for getting rid of frames :)
mikewarot · 55m ago
The reason is simple, HTML is not a hypertext markup language. Markup is the process of adding commentary and other information on top of an existing document, and HTML is ironically incapable of doing the one thing it most definitely should be able to do.
It's so bad, that if you want to discuss the markup hypertext (I.E. putting notes on top of an existing read only text files, etc.) you'll have to Google the word "annotation" to even start to get close.
Along with C macros, Case Sensitivity, Null terminated strings, unauthenticated email, ambient authority operating systems, HTML is one of the major mistakes of computing.
We should have had the Memex at least a decade ago, and we've got this crap instead. 8(
rorylaitila · 6h ago
I'm a full stack developer. I do server side rendering. I agree that this is a 'solved problem' for that case. However there are many times I don't want to run a server or a static site generator. I manage a lot of projects. I don't want more build steps than necessary. I just want to put some HTML on the net with some basic includes, without JavaScript. But currently I would go the web component route and accept the extra JS.
lerp-io · 5m ago
just use react or nextjs or whatever and move on jeez
austin-cheney · 12h ago
So, HTML did have includes and they fell out of favor.
The actual term include is an XML feature and it’s that feature the article is hoping for. HTML had an alternate approach that came into existence before XML. That approach was frames. Frames did much more than XML includes and so HTML never gained that feature. Frames lost favor due to misuse, security, accessibility, and variety of other concerns.
Linux-Fan · 12h ago
Unlike Framesets I think XML includes were never really supported in many browsers (or even any major browsers)?
I still like to use them occasionally but it incurs a "compilation" step to evaluate them prior to handing the result of this compilation to the users/browsers.
LegionMammal978 · 11h ago
As it happens, the major browsers still can do XML 'includes' to some extent, since by some miracle they haven't torn out their support for XSLT 1.0. E.g. this outputs "FizzBuzz" on Firefox:
You can even use XSLT for HTML5 output, if you're careful. But YMMV with which XML processors will support stylesheets.
ndriscoll · 11h ago
Yep, and this can be used to e.g. make a basically static site template and then do an include for `userdata.xml` to decorate your page with the logged in user's info (e.g. on HN, adding your username in the top right, highlighting your comments and showing the edit/delete buttons, etc.). You can for example include into a variable `<xsl:variable name="myinfo" select="document('userdata.xml')"/>` and then use it in xpath expressions like `$myinfo/user/@id`. Extremely simple, good for caching, lightweight, very high performance. Easy to fail gracefully to the logged out template. You basically get your data "API" for free since you're returning XML in your data model. I will never understand why it didn't take off.
XML includes are blocking because XSL support hasn't been updated for 25 years, but there's no reason why we couldn't have it async by now if resources were devoted to this instead of webusb etc.
LegionMammal978 · 10h ago
> if resources were devoted to this
You'd better not jinx it: XSL support seems like just the sort of thing browser devs would want to tear out in the name of reducing attack surface. They already dislike the better-known SVG and never add any new features to it. I often worry that the status quo persists only because they haven't really thought about it in the last 20 years.
o11c · 8h ago
Fortunately, XSLT is used by far too many high-importance websites (e.g. official government legal sites) for removing it to be a real threat.
mr_toad · 4h ago
> I will never understand why it didn't take off.
I’ve used XSLT in anger - I used it to build Excel worksheets (in XML format) using libXSLT. I found it very verbose and hard to read. And Xpath is pretty torturous.
I wish I could have used Javascript. I wish Office objects were halfway as easy to compose as the DOM. I know a lot of people hate on Javascript and the DOM, but it’s way easier to work with than the alternatives.
int_19h · 3h ago
XQuery is basically XSLT with saner syntax.
Linux-Fan · 10h ago
Nice, didn't think of that approach and It should work very well for the purposes of static headers and footers.
uallo · 12h ago
There is an open issue about this at WHATWG (also mentioned in the comment section of the blog post):
This is just my own understanding, but doesn't a webpage consist of a bunch of nodes, which can be combined in any way. And an html document is supposed to be a complete set of nodes, so a combination of those won't be a single document anymore.
Nodes can be addressed individually, but a document is the proportion for transmission containing also metadata. You can combined nodes as you like, but you can't really combined two already packed and annotated documents of nodes.
So I would say it is more due a semantic meaning. I think there was also the idea of requesting arbitrary sets of nodes, but that was never developed and with the shift away from a semantic document, it didn't make sense anymore.
gugagore · 8h ago
I think the quickest way to say it is that there is only one head on a page, and every HTML file needs a head. So if you include one into the other, you either have two heads, or the inner document didn't have a head.
econ · 7h ago
They can just be html chunks. No need to make sense on their own.
Maybe a single tag that points at an url to load if someone attempts to load the chunk directly.
> a webpage consist of a bunch of nodes, which can be combined in any way
More or less, but manipulating the nodes requires JavaScript, which some people would like to avoid.
aquova · 1h ago
I 100% agree with the sentiment of this article. For my personal website, I write pretty much every page by hand, and I have a header and a footer on most of those pages. I certainly don't want to have to update every single page everytime I want to add a new navigation button to the top of the page. For a while I used PHP, but I was running a PHP server literally for only this feature. I eventually switched to JavaScript, but likewise, on a majority of my pages, this was the only JavaScript I had, and I wanted to have a "pure" HTML page for a multitude of reasons.
In the end, I settled on using a Caddy directive to do it. It still feels like a tacked on solution, but this is about as pure as I can get to just automatically "pasting" in the code, as described in the article.
simonjgreen · 6h ago
I know it’s not straight HTML, but SSI (server side includes) helped with this and back in the day made for some incredibly powerful caching solutions. You could write out chunks of your site statically and periodically refresh them in the server side, while benefitting from serving static content to your users. (This was in the pre varnish era, and before everyone was using memcached)
I personally used this to great success on a couple of Premier League football club websites around the mid 2000s.
thayne · 5h ago
One benefit of doing it on the client is the client can cache the result of an include. So for example, instead of having to download the content of a header and footer for every page, it is just downloaded once and re-usef for future pages
Sesse__ · 5h ago
How big are your headers and footers, really? If caching them is worth the extra complexity on the client plus all the pain of cache invalidation (and the two extra requests in the non-cached case).
I don't think you even need to wrap it, really. You need to make sure it's valid XML, but the root element could be <html> just fine. And then use an identity transform with <xsl:output method="html">.
imiric · 4h ago
That's interesting, thanks.
How well supported is XSLT in modern browsers? What would be the drawbacks of using this approach for a modern website?
No HTML imports was an idea of using the HTML document format to encapsulate the 3 distinct data types needed for custom elements:
- JS for functionality via the custom elements API
- HTML for layout via <template> tags.
- CSS for aesthetics via <style> tags.
Not for just quickly and simply inserting the contents of header.html at a specific location in the DOM.
HeavyStorm · 7h ago
Says "superseded by ES modules". Not really the same thing, right?
kyledrake · 6h ago
At least some of the blame here is the bias towards HTML being something that is dynamic code generated, as opposed to something that is statically handwritten by many people.
There are features that would be good for the latter that have been removed. For example, if you need to embed HTML code examples, you can use the <xmp> tag, which makes it so you don't need to encode escapes. Sadly, the HTML5 spec is trying to obsolete the <xmp> tag even though it's the only way to make this work. All browsers seem to be supporting it anyways, but once it is removed you will always have to encode the examples.
HTML spec developers should be more careful to consider people hand coding HTML when designing specifications, or at least decisions that will require JavaScript to accomplish something it probably shouldn't be needed for.
TZubiri · 6h ago
It's the other way around, HTML was designed to be hand written, and the feature set was defined at that stage. If it ended up being dynamically generated, that happened after the feature set was defined.
_heimdall · 11h ago
If I really need HTML includes for some reason, I'd reach for XSLT. I know its old, and barely maintained at best, but that was the layer intentionally added to add programming language features to the markup language that is HTML.
My main gripe is a decade(s?) old Firefox bug related to rendering an HTML string to the DOM.
That may be a fairly specific use case though, and largely it still works great today. I've done a few side projects with XSLT and web components for interactivity, worked great.
mark_and_sweep · 4h ago
What bug specifically?
_heimdall · 2h ago
Couldn't find a good link earlier, guess I didn't have quite the right keywords for search.
I think XSLT is still a reasonable technology in itself - the lack of updated implementations is the bad part. I think modern browsers only support 1.0 (?). At least most modern programming languages should have 3.0 support.
_heimdall · 6h ago
Firefox has a very old bug related to rendering an HTML string to the DOM without escaping it, that one has bit me a few times. Nothing a tiny inline script can't fix, but its frustrating to have such a basic feature fail.
Debugging is also pretty painful, or I at least haven't found a good dev setup for it.
That said, I'm happy to reach for XSLT when it makes sense. Its pretty amazing what can be done with such an old tech, for the core use case of props and templates to HTML you really don't need react.
evrimoztamur · 13h ago
If you want to include HTML sandboxes, we have iframes. If you want it served from the server, it's just text. Putting text A inside text B is a solved problem.
esperent · 12h ago
> Putting text A inside text B is a solved problem.
Yes, but in regards to HTML it hasn't been solved in a standard way, it's been solved in hundreds, if not thousands of non standard ways. The point of the article is that having one standard way wlcould reduce a lot of complexity from the ecosystem, as ES6 imports did.
zamadatix · 12h ago
The article references both of these methods with explanations of why they don't feel they answer the question posed.
bambax · 12h ago
> We’ve got <iframe>, which technically is a pure HTML solution, but they are bad for overall performance, accessibility, and generally extremely awkward here
What does this mean? This is a pure HTML solution, not just "technically" but in reality. (And before iframe there were frames and frameset). Just because the author doesn't like them don't make them non-existent.
jadamson · 12h ago
What do you mean what does it mean?
An iframe is a window into another webpage, and is bounded as such both visually and in terms of DOM interfaces. A simple example would be that an iframe header can't have drop-down menus that overlap content from the page hosting it.
They are categorically not the same DX/UX as SSI et al. and it's absolutely bizarre to me that there's so many comments making this complaint.
silvestrov · 12h ago
The real problem with iframes is that their size is set by the parent document only.
They would be a lot more useful if we could write e.g. <iframe src=abc.html height=auto width=100> so the height of the iframe element is set by the abc.html document instead of the parent document.
jefftk · 8h ago
You could do this with js in the child document, if its important to keep js out of the parent.
baggy_trough · 9h ago
You can achieve that with js in the parent document.
teg4n_ · 8h ago
You can achieve everything with JS in the parent document, it doesn’t mean it should be required or even recommended
ajkjk · 12h ago
No way. You can't make a decent single web page by iframing a bunch of components together.
jsdwarf · 8h ago
I'd say in 80% of the cases a pure, static html include is not enough. In a menu include, you want to disable the link to the currently shown page or show a page specific breadcrumb.
In a footer include, you may want a dynamic "last updated" timestamp or the current year in the copyright notice.
As all these use cases required a server-side scripting language anyway, there was no push behind an html include.
> I don't think we should do this. The user experience is much better if such inclusion is done server-side ahead of time, instead of at runtime. Otherwise, you can emulate it with JavaScript, if you value developer convenience more than user experience.
The "user experience" problem he's describing is a performance problem, adding an extra round-trip to the server to fetch the included HTML. If you request "/blog/article.html", and the article includes "/blog/header.html", you'll have to do another request to the server to fetch the header.
It would also prevent streaming parsing and rendering, where the browser can parse and render HTML bit-by-bit as it streams in from the server.
Before you say, "so, what's the big deal with adding another round trip and breaking the streaming parser?" go ahead and read through the hundreds of comments on that thread. "What's the big deal" has not convinced browser devs for at least eight years, so, pick another argument.
I think there is a narrow opening, where some noble volunteer would spec out a streaming document-fragment parser.
It would involve a lot of complicated technical specification detail. I know a thing or two about browser implementation and specification writing, and designing a streaming document-fragment parser is far, far beyond my ken.
But, if you care about this, that's where you'd start. Good luck!
P.S. There is another option available to you: it is kinda possible to do client-side includes using a service worker. A service worker is a client-side proxy server that the browser will talk to when requesting documents; the service worker can fetch document fragments and merge them together (even streaming fragments!) with just a bit of JS.
But that option kinda sucks as a developer experience, because the service worker doesn't work the first time a user visits your site, so you'd have to implement server-side includes and also serve up document fragments, just for second-time visitors who already have the header cached.
Still, if all you want is to return a fast cached header while the body of your page loads, service workers are a fantastic solution to that problem.
SJC_Hacker · 12h ago
Initially HTML was less about the presentation layer and more about the "document" concept. Documents should be self-contained, outside of references to other documents.
spauldo · 1h ago
One document == one HTML page was never the idea. Documents are often way too long to comfortably read and navigate that way. Breaking them into sections and linking between them was part of the core idea of HTML.
Includes are a standard part of many document systems. Headers and footers are a perfect example - if I update a document I certainly don't want to update the document revision number on every single page! It also allows you to add navigation between documents in a way that is easy to maintain.
LaTeX can do it. Microsoft Word can do it (in a typically horrible Microsoftian way). Why not HTML?
skydhash · 12h ago
I still think this is the best web. Either you are a collection of interlinked documents and forms (manual pages, wiki,...), or you are a full application (figma, gmail, google docs). But a lot of sites are trying to be both. And somes are trying to be one while they are the other type.
djoldman · 11h ago
> Our developer brains scream at us to ensure that we’re not copying the exact code three times, we’re creating the header once then “including” it on the three (or a thousand) other pages.
Interesting, my brain is not this way: I want to send a minimum number of files per link requested. I don't care if I include the same text because the web is generally slow and it's generally caused by a zillion files sent and a ton of JS.
esprehn · 12h ago
We discussed this back when creating web components, but the focus quickly became about SPA applications instead of MPAs and the demand for features like this was low in that space.
I wish I would have advocated more for it though. I think it would be pretty easy to add using a new attribute on <script> since the parser already pauses there, so making something like <script transclude={url}> would likely not be too difficult.
SSI is still a thing: I use it on my personal website. It isn't really part of the HTML, though: it's a server-dependent extension to HTML. It's supported by Apache and nginx, but not by every server, so you have to have control over the server stack, not just access to the documents.
simultsop · 5h ago
It's a pity, of all web resources advancements, js, css, runtimes, web engines. HTML was the most stagnant aspect of it, despite the "HTML5" effing hype. My guess is they did not want to empower HTML and threaten SSR's, or solutions. I believe the bigest concern of not making a step is the damned backward compatibility. Some just wont budge to move.
Andrex · 1h ago
HTML5 hype started strong out of the gate because of the video and audio tags, and canvas slightly after. Those HTML tags were worth the hype.
Flash's reputation was quite low at the time and people were ready to finally move on from plugins being required on the web. (Though the "battle" then shifted to open vs. closed codecs.)
ludwik · 11h ago
We used to have this in the form of a pair of HTML tags: <frameset> and <frame> (not to be confused with the totally separate <iframe>!). <frameset> provided the scaffolding with slots for multiple frames, letting you easily create a page made up entirely of subpages. It was once popular and, in many ways, worked quite neatly. It let you define static elements once entirely client-side (and without JS!), and reload only the necessary parts of the page - long before AJAX was a thing. You could even update multiple frames at once when needed.
From what I remember, the main problem was that it broke URLs: you could only link to the initial state of the page, and navigating around the site wouldn't update the address bar - so deep linking wasn’t possible (early JavaScript SPA frameworks had the same issue, BTW). Another related problem was that each subframe had to be a full HTML document, so they did have their own individual URLs. These would get indexed by search engines, and users could end up on isolated subframe documents without the surrounding context the site creator intended - like just the footer, or the article content without any navigation.
miragecraft · 6h ago
I too lamented the loss of HTML imports and ended up coming up with my own JavaScript library for it.
At the end of the day it’s not something trivial to implement at the HTML spec/parser level.
For relative links, how should the page doing the import handle them?
Do nothing and let it break, convert to absolute links, or remap it as a new relative link?
Should the include be done synchronously or asynchronously?
The big benefit of traditional server side includes is that its synchronous, thus simplifying logic for in-page JavaScript, but all browsers are trying to eliminate synchronous calls for speed, it’s hard to see them agreeing to add a new synchronous bottleneck.
Should it be CORS restricted? If it is then it blocks offline use (file:// protocol) which really kills its utility.
There are a lot of hurdles to it and it’s hard to get people to agree on the exact implementation, it might be best to leave it to JavaScript libraries.
neuroelectron · 6h ago
So glad I decided early in my career to not do webpages. Look how much discussion this minor feature has generated. I did make infra tools that outputted basic html, get post cgi type of stuff. What's funny is this stuff was deployed right before AWS was launched and a year later the on prem infra was sold and the warehouse services were moved to the cloud.
spauldo · 1h ago
You and me both. I did some web dev back in the early days, and noped out when IE was dragging everyone down with its refusal to change. I have never had a reason to regret that decision.
somethingsome · 12h ago
I'm not an expert on this but IMO, from a language point of view, HTML is a markup language, it 'must' have no logic or processing. It is there to structure the information not to dynamically change it. Nor even to display it nicely.
The logic is performed elsewhere. If you were to have includes directly in HTML, it means that browsers must implement logic for HTML. So it is not 'just' a parser anymore.
Imagine for example that I create an infinite loop of includes, who is responsible to limit me? How to ensure that all other browsers implement it in the same way?
What happens if I perform an injection from another website? Then we start to have cors policy management to write. (iframes were bad for this)
Now imagine using Javascript I inject an include somewhere, should the website reload in some way? So we have a dynamic DOM in HTML?
naasking · 11h ago
> from a language point of view, HTML is a markup language, it 'must' have no logic or processing.
Client-side includes are not "processing". HTML already has frames and iframes which do this, just in a worse way, so we'd be better off.
somethingsome · 9h ago
I understand your point, but I still think it is bad from the point of view of language paradigms[1]. Iframes should have not been created in the first place.. You are changing the purpose of the language while it was not made for it.
(yes in my view I interpret includes as a basic procedure)
There is a very, very broad line in that "no logic or processing". HTML/CSS already do a lot of logic and processing. And many "markup languages" have include support. Like wikitext used in wikipedia and includes in Asciidoc.
jasoncartwright · 12h ago
I made this to get around pages being cached at CDN level, but still needing to get live data...
I think it’s because it would be so easy to make a recursive page that includes itself forever. So you have to have rules when it’s okay, and that’s more complex and opaque than just programming it yourself.
DJHenk · 12h ago
My guess: no-one needs it.
Originally, iframe were the solution, like the posts mentions. By the time iframes became unfashionable, nobody was writing HTML with their bare hands anymore. Since then, people use a myriad of other tools and, as also mentioned, they all have a way to fix this.
So the only group who would benefit from a better iframe is the group of people who don't use any tools and write their HTML with their bare hands in 2025. That is an astonishing small group. Even if you use a script to convert markdown files to blog posts, you already fall outside of it.
No-one needs it, so the iframe does not get reinvented.
Svip · 12h ago
No, originally frameset[0] and frame[1] were the solution to this problem. I remember building a website in the late 1990s with frameset. iframe came later, and basically allowed you to do frames without the frameset. Anyway, frameset is also the reason every browser's user agent starts with "Mozilla".
what if it could be a larger group though? modern css has been advancing rather rapidly... I don't even need a preprocessing library any more... I've got nested rules, variables, even some light data handling... why not start beefing up html too? we've got some new features but includes would be killer
WhyNotHugo · 5h ago
HTML frames solved this problems just fine, but they were deprecated in favour of using AJAX to replace portions of the body as you navigate (e.g.: SPAs).
I still feel like frames were great for their use case.
daveac · 6h ago
I desperately want to back to crafting sites by hand and not reach for react/vue as a default. I do a lot of static and tempory sites that do very little
insin · 3h ago
Astro is all the goodness of components but for static sites.
chipsrafferty · 6h ago
Use HTMX.
prkl · 12h ago
honestly, html can include css and javascript via link and style tags. there's no reason for it to not have an <include src="" /> tag, and let the browser parsing it fetch the content to replace it.
franze · 7h ago
Now you can include HTML in HTML, see https://include.franzai.com/ - a quick Chrome Polyfill based on the discussion here. MIT License
HTML does have frames and iframes, which can accomplish some of the same goals.
mirkodrummer · 4h ago
it is mentioned in the article indeed; it's an awful solution that is poor in performance and break the accessibility
paulryanrogers · 56m ago
Thanks. I was reading too fast and missed the iframe reference in the article
mixmastamyk · 4h ago
Why would the performance be any better with another tag?
rhet0rica · 3h ago
A frame is a separate rendering context—it's (almost) as heavyweight as a new tab. The author wants to insert content from another file directly into the existing DOM, merging the two documents completely.
mixmastamyk · 3h ago
Negligible twenty years ago. But yes, if there's an improvement it should be merged automatically into the same document.
bandrami · 4h ago
Because how would the browser decide it's in a fetch loop?
nsonha · 42m ago
the web platform is the tech stack version of the human concept of "failing upward". It sucks but will only get more and more vital in the modern tech scene as time goes by.
johannes1234321 · 12h ago
I would guess back in the days having extra requests was expensive, thus discouraged. Later there were attempts via xinclude, but by then PHP and similar took over or people tolerated frames.
dietsche · 6h ago
I think the authors of htmx have the same questions :)
mmastrac · 12h ago
Do remote entity references still work in XHTML? XML had its issues but did have a decent toolbox of powerful if not insecure primitives.
That's the first thing listed in the article? "Javascript to go fetch the HTML and insert it". What they're after is something that's _just_ HTML and not another language.
sreekotay · 7h ago
While you do need a server i think this is the functional equivalent? The fetch JS and insert outlined (linked to) in the article is async. This blocks execution like you'd expect an HTML include to do. It's WAY easier to reason about - which is why the initial ask, I think...
j45 · 3h ago
The <object> tag appears to include/embed other html pages.
you need a server for HTML to work, as practical matter. But yes. There IS a workaround to that too, if you're REALLY determined, but you have to format your HTML a giant JS comment block (lol really :))
[edit: I'm sure there are still some file:// workflows for docs - and yes this doesn't address that]
mattl · 5h ago
You don't need a server for HTML to work, I can just hand you a USB stick/floppy disk/MO disk for your NeXT with HTML files on it.
sreekotay · 4h ago
( •_•)
( •_•)>⌐■-■
(⌐■_■)
Deal with it.
:)
bdcravens · 13h ago
The simplest answer is that HTML wasn't designed as a presentation language, but a hypertext document language. CSS and Javascripts were add-ons after the fact. Images weren't even in the first version. Once usage of the web grew beyond the initial vision, solutions like server-side includes and server-side languages that rendered HTML were sufficient.
skydhash · 12h ago
I think the best examples of HTML in that regard is HTML-rendered info pages[0], for Emacs and its ecosystem. Then you have the same content presented in HTML [1]. Templates were enough in the first case. Includes are better in the second case due to common assets external to the content.
I guess for the similar reason that Markdown does not have any "include" ability -- it is a feature not useful enough yet with too many issues to deal with. They are really intended to be used as "single" documents.
dinkblam · 7h ago
we had no problem using <object> for headers and footers
That's mentioned in TFA under "old school web server directives".
rsolva · 12h ago
After researching this very topic earlier; SSI is the most pragmatic solution. Check out Caddy's Template Language (based on Go), it is quite capable and quite similar to building themes in Hugo. Just much more bare bones.
I have built several sites with pure HTML+CSS, sprinkled with some light SSI with Caddy, and it is rock solid and very performant!
mixmastamyk · 4h ago
Lots of rationalization in here—it's always been needed. I complained about the lack of <include src="..."> when building my first site in '94/95, with simpletext and/or notepad!
It was not in the early spec, and seems someone powerful wouldn't allow it in later. So everyone else made work arounds, in any way they could. Resulting in the need being lessened quite a bit.
My current best workaround is the <object data=".."> tag, which has a few better defaults than iframe. If you put a link to the same stylesheet in the include file it will match pretty well. Size with width=100%, though with height you'll need to eyeball or use javascript.
Seems everyone forgot HTML-SSI which worked something like this. Many servers and hosting websites of the 90s supported it.
<!--#include virtual="header.html" -->
Some content here
<!--#include virtual="footer.html" -->
TZubiri · 6h ago
Because it's HyperText, the main idea is that you link to other content, so this is not a weird feature that is being asked for, it's just a different way of doing the whole raison d'etre of the tech. In fact the tag to link stuff is the <a> tag. It just so happens that it makes you load the other "page", instead of transcluding content, the idea is that you load it.
It wouldn't make sense to transclude the article about the United States in the article about Wyoming (and in fact modern wikipedia shows a pop up bubble doing a partial transclusion, but would benefit in no way from basic html transclusion.)
It's a simple idea. But of course modern HTML is not at all what HTML was designed to be, but that's the canonical answer.
The elders of HTML would just tell you to make an <a> link to whatever you wanted to transclude instead. Be it a "footer/header/table of contents" or another encylcopdic article, or whatever. Because that's how HTML works, and not the way you suggest.
Think of what would happen if it were the case, you would transclude page A, which transcludes page B, and so with page C, possibly recursively transcluding page B and so. You would transform the User Agent (browser) into a whole WWW crawler!
It's because HTML is pass by reference, not pass by copy.
tiku · 8h ago
iFrames have a src and includes other html.. We used to make sites with it way back.
Imustaskforhelp · 12h ago
I think this is a genuinely good question that I was also wondering some time ago.
And it is a genuinely good question!
I think the answer of PD says feels the truest.
JS/CSS with all its bureaucracy are nothing compared to HTML it seems. Maybe people don't find nothing wrong with Html, maybe if they do, they just reach out for js/css and try to fix html (ahem frontend frameworks).
That being said, I have just regurgitated what PD says has said and I give him full credit of that but I am also genuinely confused as to why I have heard that JS / CSS are bureaucratic (I remember that there was this fireship video of types being added in JS and I think I had watched it atleast 1 year ago (can be wrong) but I haven't heard anything for it and I see a lot of JS proposals just stuck from my observation
And yet HTML is such level of bureaucratic that the answer to why HTML doesn't have a feature is because of its bureaucracy. Maybe someone can explain the history of it and why?
axelfontaine · 13h ago
Iframes, while not perfect, are pretty close though...
lelandfe · 13h ago
Making iframes be the right size is super awkward. I might actually use them more if they were easy to get responsive.
This post does link to a technique (new to me) to extract iframe contents:
Are we solving the information-centric transclusion problem,
or the design-centric asset reuse problem?
An iframe is fine for the former but is not geared towards design and layout solutions.
lelandfe · 11h ago
It kinda sucks for both! Dropping in a box of text that flatly does not resize to fit its contents does not fit the definition of "fine" for me, here.
You can do some really silly maneuvers with `window.postMessage` to communicate an expected size between the parent and frame on resize, but that's expensive and fiddly.
webstrand · 12h ago
Iframes fundamentally encapsulate html documents, not fragments.
rendaw · 12h ago
Interaction between elements in different iframes is very restricted.
danans · 12h ago
IIRC, you can communicate entire JSON objects between an iframe and it's host frame with PostMessage.
The host can then act as a server for the iframe client, even updating it's state or DOM in response to a message from the iframe.
Devasta · 5h ago
Honest answer: because any serious efforts to improve HTML died 20 years ago, and the web as it's envisaged today is not an infinite library of the worlds knowledge but instead a JavaScript based and platform.
Asking for things that the W3C had specced out in 2006 for XML tech is just not reasonable if it doesn't facilitate clicks.
bufferoverflow · 12h ago
iframe is html
nico · 13h ago
FTA
> We’ve got <iframe>, which technically is a pure HTML solution, but
And then on the following paragraph..
> But none of the solutions is HTML
> None of these are a straightforward HTML tag
Not sure what the point is. Maybe just complaining
ComplexSystems · 12h ago
<iframe> is different from what the author is asking for, it has its own DOM and etc. He wants something like an SSI but client side. He explains some of the problems right after the part you cut off above
"We’ve got <iframe>, which technically is a pure HTML solution, but they are bad for overall performance, accessibility, and generally extremely awkward here"
pjc50 · 13h ago
Iframe is stuck in a rectangular box. It's not really suitable for things like site wide headers, footers and menus.
vlovich123 · 12h ago
While I get your point, headers and footers and menus tend to all live within rectangular boxes.
zamadatix · 12h ago
Headers and their menus are often problematic for this approach, unless they are 100% static (e.g. HN would work but Reddit and Google wouldn't since they both put things in their header which can expand over the content). I.e. you can make it transparent but that doesn't solve eating the interactions. The code needed to work around that is more than just using JS to do the imports.
jefftk · 8h ago
Headers and footers, yes. Menus generally need to expand when you interact with them, especially on mobile.
teg4n_ · 8h ago
Do a drop down list of links on a header in an iframe
Strict documents, reusable types, microformats, etc. would have put search into the hands of the masses rather than kept it in Google's unique domain.
The web would have been more composible and P2P. We'd have been able to slurp first class article content, comments, contact details, factual information, addresses, etc., and built a wealth of tooling.
Google / WhatWG wanted easy to author pages (~="sloppy markup, nonstandard docs") because nobody else could "organize the web" like them if it was disorganized by default.
Once the late 2010's came to pass, Google's need for the web started to wane. They directly embed lifted facts into the search results, tried to push AMP to keep us from going to websites, etc.
Google's decisions and technologies have been designed to keep us in their funnel. Web tech has been nudged and mutated to accomplish that. It's especially easy to see when the tides change.
The <object> tag appears to include/embed other html pages.
An embedded HTML page:
<object data="snippet.html" width="500" height="200"></object>
https://www.w3schools.com/tags/tag_object.asp
https://en.wikipedia.org/wiki/Billion_laughs_attack
Yeah, we’ve been solving this over and over in different ways. For those saying that iframes are good enough, they’re not. Iframes don’t expand to fit content. And server side solutions require a server. Why not have a simple client side method for this? I think it’s a valid question. Now that we’re fixing a lot of the irritation in web development, it seems worth considering.
A small 10KB lib that augments HTML with the essential good stuff (like dynamic imports of static HTML)
My dialup ISP back then didn't disable using .htaccess files in the web space they provided to end users. That meant I could turn on server-side includes! Later I figured out how to enable CGI. (I even went so far as to code rudimentary webshells in Perl just so I could explore the webserver box...)
Actually, that was part of the original plan - https://caniuse.com/iframe-seamless
It worked rather like a reverse shadow DOM, allowing CSS from the parent document to leak into the child, removing borders and other visual chrome that would make it distinguishable from the host, except you still had to use fixed CSS layouts and resize it with JS.
This helps the creator, but not the consumer, right? That is, if I visit 100 of your static documents created with a template engine, then I'll still be downloading some identical content 100 times.
On the other hand it means less work for the client, which is a pretty big deal on mobile.
XSLT did exactly what HTML includes could do and more. The user agent could cache stylesheets or if it wanted override a linked stylesheet (like with CSS) and transform the raw data any way it wanted.
While it evaluated the xslt serverside it was a really neat and simple approach.
We’ve built an industry around solving this problem. What if, for some basic web publishing use cases, we could replace a complex web framework with one new tag?
<div src="foo.txt"></div>
> XHTML 2 takes a completely different approach, by taking the premise that all images have a long description and treating the image and the text as equivalents. In XHTML 2 any element may have a @src attribute, which specifies a resource (such as an image) to load instead of the element.
Like writing a line of js?
If internally this gets optimized to a simple I/O operation (which it should) then why add the JS indirection in the first place?
To me includes for HTML should work in the dumbest way possible. And that means: Take the text from the include and paste it where the include was and give the browser the resulting text.
If you want to cache a nav section separately because it appears the same on every page lets add a cache attribute that solves the problem independently:
To tell the browser it should load the inner html or the src of that element from cache if it has it.Now you could convince me thst the include should allow for more, but it being dumb is a feature not a bug.
I’m sure some purist argument has driven this somewhere.
All sorts of data could be linked together to display or remix by user agents.
Markdown can't do most of those, so it makes more sense why it doesn't have includes, but I'd still argue it definitely should. I generally dislike LaTeX, but about the only thing I liked about it when writing my thesis was that I could have each chapter in its own file and just include all of them in the main file.
As I wrote that, I realized there could be cumulative layout shift, so that’s an argument against. To avoid that, the browser would have to download all transcluded content before rendering. In the past, this would have been a dealbreaker, but maybe it’s more feasible now with http multiplexing.
[0] https://en.m.wikipedia.org/wiki/Transclusion#Client-side_HTM...
https://docs.asciidoctor.org/asciidoc/latest/directives/incl...
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I'm not defending it, because when I started web development this was one of the first problems I ran into as well -- how the heck do you include a common header.
But the original concept of HTML was standalone documents, not websites with reusable components like headers and footers and navbars.
That being said, I still don't understand why then the frames monstrosity was invented, rather than a basic include. To save on bandwidth or something?
A link in a sidebar frame would open a link in the "editor" frame which loaded a page with a normal HTML form. Submitting the form reloaded it in that same frame. Often the form would have multiple submit buttons, one to save edits in progress and another to submit the completed form and move to the next step. The current app state was maintained server side and validation was often handled there save for some basic formatting client side JavaScript could handle.
This setup allowed even the most primitive frame-supporting browsers to use CRUD web apps. IIRC early web frameworks like WebObjects leaned into that model of web app.
They were horrible -- you'd hit the back button and only one of the frames would go back and then the app would be in an inconsistent state... it was a mess!
I don't love JavaScript monstrosities but XHR and dynamic HTML were a vast improvement over HTML forms and frame/iframe abuse.
Lots of gateways between systems.
It’s made to pull in external resources (as opposed to other document formats like PDF).
Scripts, stylesheets, images, objects, favicons, etc. HTML is thematically similar.
The only one that is presentational is stylesheets.
https://developer.mozilla.org/en-US/docs/Web/CSS/content
> HTML Imports are a way to include and reuse HTML documents in other HTML documents
There were plans for <template> tag support and everything.
If I remember correctly, Google implemented the proposed spec in Blink but everyone else balked for various reasons. Mozilla was concerned with the complexity of the implementation and its security implications, as well as the overlap with ES6 modules. Without vendor support, the proposal was officially discontinued.
[1] https://www.w3.org/TR/html-imports/
The thing is that all those are non-reasons that don't really explain anything: Low demand is hard to believe if this feature is requested for 20 years straight and there are all kinds of shim implementations using scripts, backend engines, etc. (And low demand didn't stop other features that the vendors were interested in for their own reasons)
Vendor refusal also doesn't explain why they refused it, even to the point of rolling back implementations that already existed.
So I'd be interested to understand the "various reasons" in more detail.
"Security implications" also seem odd as you already are perfectly able to import HTML cross origin using script tags. Why is importing a script that does document.write() fine, but a HTML tag that does exactly the same thing hugely problematic?
(I understand the security concern that you wouldn't want to allow something like "<import src=google.com>" and get an instant clone of the Google homepage. But that issue seems trivially solvable with CORS.)
[1] https://frontendmasters.com/blog/seeking-an-answer-why-cant-...
See https://github.com/whatwg/html/issues/2791#issuecomment-3112... for details.
https://web.archive.org/web/19970630074729fw_/http://develop...
https://web.archive.org/web/19970630094813fw_/http://develop...
https://en.wikipedia.org/wiki/Transclusion
It was part of Project Xanadu, and originally considered to be an important feature of hypertext.
Notably, mediawiki uses transclusion extensively. It sometimes feels like the wiki is the truest form of hypertext.
it never quite took off
If main.html includes child/include1.html and child/include1.html has a link src="include2.html" then when the user clicks the link where does it go? If it goes to "include2.html", which by the name was meant to be included, then that page is going to be missing everything else. If it goes to main.html, how does it specify this time, use include2.html, not include1.html?
You could do the opposite, you can have article1.html, article2.html, article3.html etc, each include header.html, footer.html, navi.html. Ok, that works, but now you've make it so making a global change to the structure of your articles requires editing all articles. In other words, if you want to add comments.html to every article you have to edit all articles and you're back to wanting to generate pages from articles based on some template at which point you don't need the browser to support include.
I also suspect there would be other issues, like the header wants to know the title, or the footer wants a next/prev link, which now require some way to communicate this info between includes and you're basically back to generate the pages and include not being a solution
I think if you work though the issues you'll find an HTML include would be practically useless for most use cases.
> If main.html includes child/include1.html and child/include1.html has a link src="include2.html" then when the user clicks the link where does it go? If it goes to "include2.html", which by the name was meant to be included, then that page is going to be missing everything else. If it goes to main.html, how does it specify this time, use include2.html, not include1.html?
There are two distinct use cases here: snippet reuse and embeddable self-contained islands. But the latter is already handled by iframes (the behavior being your latter case). So we only need to do the former.
As the article says, the problem is a solved one. The "includes" issue is how every web design student learns about PHP. In most CMSes, "includes" become "template partials" and are one of the first things explained in the documentation.
There really isn't any need to make includes available through just HTML. HTML is a presentation format and doesn't do anything interesting without CSS and JS anyway.
That's not an argument that client-side includes shouldn't happen. In fact HTML already has worse versions of this via frames and iframes. A client-side equivalent of a server-side include fits naturally into what people do with HTML.
Exactly! Include makes perfect sense on server-side.
But client-side include means that the client should be able to modify original DOM at unknown moment of time. Options are
1. at HTML parse time (before even DOM is generated). This requires synchronous request to server for the inclusion. Not desirable.
2. after DOM creation: <include src=""> (or whatever) needs to appear in the DOM, chunk loaded asynchronously and then the <include> DOM element(sic!) needs to be replaced(or how?) by external fragment. This disables any existing DOM structure validation mechanism.
Having said that...
I've implemented <include> in my Sciter engine using strategy #1. It works there as HTML in Sciter usually comes from local app resources / file system where price of issuing additional "get chunk" request is negligible.
See: https://docs.sciter.com/docs/HTML/html-include
Some content is already loaded asynchronously such as images, content below the fold etc.
> HTML is really just a markup syntax, not a programming language
flamebait detected :) It's a declarative language, interpreted by each browser engine separately.
<html src="/some/page.html">, <div src="/some/div.html">, <span src="/some/span.html">, etc.
Or create a new tag that's a noun like fragment, page, document, subdoc or something.
Surely that's no less markup than svg, img, script, video, iframe, and what not.
No comments yet
Nor is this something unique to SGML. XML is also a "markup language", yet XInclude is a thing.
> considered to be server-side
Good point! Wouldn't fetching a template partial happen the same way (like fetching an image?)
I always assumed it stood for my initials.
HTML is a markup language that identifies the functional role of bits of text. In that sense, it is there to provide information about how to present the text, and is thus a presentation format.
It is also a document description language, because almost all document description languages are also a presentation format.
There was a lot of criticism for frames [1] but still they were successfully deployed for useful stuff like Java API documentation [2].
In my opinion the whole thing didn't stay mostly because of too little flexibility for designer: Framesets were probably well enough for useful information pages but didn't account for all the designers' needs with their bulky scrollbars and limited number of subspaces on the screen. Today it is too late to revive them because framesets as-is wouldn't probably work well on mobile...
[1] <https://www.nngroup.com/articles/why-frames-suck-most-of-the...> - I love how much of it is not applicable anymore and all of these problems mentioned with frames are present in today's web in an even nastier way?
[2] <https://www.eeng.dcu.ie/~ee553/ee402notes/html/figures/JavaD...>
Of course "back then" this was an important feature and one of the reasons for getting rid of frames :)
It's so bad, that if you want to discuss the markup hypertext (I.E. putting notes on top of an existing read only text files, etc.) you'll have to Google the word "annotation" to even start to get close.
Along with C macros, Case Sensitivity, Null terminated strings, unauthenticated email, ambient authority operating systems, HTML is one of the major mistakes of computing.
We should have had the Memex at least a decade ago, and we've got this crap instead. 8(
The actual term include is an XML feature and it’s that feature the article is hoping for. HTML had an alternate approach that came into existence before XML. That approach was frames. Frames did much more than XML includes and so HTML never gained that feature. Frames lost favor due to misuse, security, accessibility, and variety of other concerns.
I still like to use them occasionally but it incurs a "compilation" step to evaluate them prior to handing the result of this compilation to the users/browsers.
XML includes are blocking because XSL support hasn't been updated for 25 years, but there's no reason why we couldn't have it async by now if resources were devoted to this instead of webusb etc.
You'd better not jinx it: XSL support seems like just the sort of thing browser devs would want to tear out in the name of reducing attack surface. They already dislike the better-known SVG and never add any new features to it. I often worry that the status quo persists only because they haven't really thought about it in the last 20 years.
I’ve used XSLT in anger - I used it to build Excel worksheets (in XML format) using libXSLT. I found it very verbose and hard to read. And Xpath is pretty torturous.
I wish I could have used Javascript. I wish Office objects were halfway as easy to compose as the DOM. I know a lot of people hate on Javascript and the DOM, but it’s way easier to work with than the alternatives.
Client side include feature for HTML
https://github.com/whatwg/html/issues/2791
Nodes can be addressed individually, but a document is the proportion for transmission containing also metadata. You can combined nodes as you like, but you can't really combined two already packed and annotated documents of nodes.
So I would say it is more due a semantic meaning. I think there was also the idea of requesting arbitrary sets of nodes, but that was never developed and with the shift away from a semantic document, it didn't make sense anymore.
Maybe a single tag that points at an url to load if someone attempts to load the chunk directly.
More or less, but manipulating the nodes requires JavaScript, which some people would like to avoid.
In the end, I settled on using a Caddy directive to do it. It still feels like a tacked on solution, but this is about as pure as I can get to just automatically "pasting" in the code, as described in the article.
I personally used this to great success on a couple of Premier League football club websites around the mid 2000s.
<script src="/include/footer.html">
For /footer.html
But then you probably might as well use server side includes
https://github.com/Evidlo/xsl-website
How well supported is XSLT in modern browsers? What would be the drawbacks of using this approach for a modern website?
https://caniuse.com/imports
- JS for functionality via the custom elements API - HTML for layout via <template> tags. - CSS for aesthetics via <style> tags.
Not for just quickly and simply inserting the contents of header.html at a specific location in the DOM.
There are features that would be good for the latter that have been removed. For example, if you need to embed HTML code examples, you can use the <xmp> tag, which makes it so you don't need to encode escapes. Sadly, the HTML5 spec is trying to obsolete the <xmp> tag even though it's the only way to make this work. All browsers seem to be supporting it anyways, but once it is removed you will always have to encode the examples.
HTML spec developers should be more careful to consider people hand coding HTML when designing specifications, or at least decisions that will require JavaScript to accomplish something it probably shouldn't be needed for.
That may be a fairly specific use case though, and largely it still works great today. I've done a few side projects with XSLT and web components for interactivity, worked great.
Here we go, looks like its 17 years old now:
https://bugzilla.mozilla.org/show_bug.cgi?id=98168#c99
Debugging is also pretty painful, or I at least haven't found a good dev setup for it.
That said, I'm happy to reach for XSLT when it makes sense. Its pretty amazing what can be done with such an old tech, for the core use case of props and templates to HTML you really don't need react.
Yes, but in regards to HTML it hasn't been solved in a standard way, it's been solved in hundreds, if not thousands of non standard ways. The point of the article is that having one standard way wlcould reduce a lot of complexity from the ecosystem, as ES6 imports did.
What does this mean? This is a pure HTML solution, not just "technically" but in reality. (And before iframe there were frames and frameset). Just because the author doesn't like them don't make them non-existent.
An iframe is a window into another webpage, and is bounded as such both visually and in terms of DOM interfaces. A simple example would be that an iframe header can't have drop-down menus that overlap content from the page hosting it.
They are categorically not the same DX/UX as SSI et al. and it's absolutely bizarre to me that there's so many comments making this complaint.
They would be a lot more useful if we could write e.g. <iframe src=abc.html height=auto width=100> so the height of the iframe element is set by the abc.html document instead of the parent document.
The first naysayer was @dominic: https://github.com/whatwg/html/issues/2791#issuecomment-3113...
> I don't think we should do this. The user experience is much better if such inclusion is done server-side ahead of time, instead of at runtime. Otherwise, you can emulate it with JavaScript, if you value developer convenience more than user experience.
The "user experience" problem he's describing is a performance problem, adding an extra round-trip to the server to fetch the included HTML. If you request "/blog/article.html", and the article includes "/blog/header.html", you'll have to do another request to the server to fetch the header.
It would also prevent streaming parsing and rendering, where the browser can parse and render HTML bit-by-bit as it streams in from the server.
Before you say, "so, what's the big deal with adding another round trip and breaking the streaming parser?" go ahead and read through the hundreds of comments on that thread. "What's the big deal" has not convinced browser devs for at least eight years, so, pick another argument.
I think there is a narrow opening, where some noble volunteer would spec out a streaming document-fragment parser.
It would involve a lot of complicated technical specification detail. I know a thing or two about browser implementation and specification writing, and designing a streaming document-fragment parser is far, far beyond my ken.
But, if you care about this, that's where you'd start. Good luck!
P.S. There is another option available to you: it is kinda possible to do client-side includes using a service worker. A service worker is a client-side proxy server that the browser will talk to when requesting documents; the service worker can fetch document fragments and merge them together (even streaming fragments!) with just a bit of JS.
But that option kinda sucks as a developer experience, because the service worker doesn't work the first time a user visits your site, so you'd have to implement server-side includes and also serve up document fragments, just for second-time visitors who already have the header cached.
Still, if all you want is to return a fast cached header while the body of your page loads, service workers are a fantastic solution to that problem.
Includes are a standard part of many document systems. Headers and footers are a perfect example - if I update a document I certainly don't want to update the document revision number on every single page! It also allows you to add navigation between documents in a way that is easy to maintain.
LaTeX can do it. Microsoft Word can do it (in a typically horrible Microsoftian way). Why not HTML?
Interesting, my brain is not this way: I want to send a minimum number of files per link requested. I don't care if I include the same text because the web is generally slow and it's generally caused by a zillion files sent and a ton of JS.
I wish I would have advocated more for it though. I think it would be pretty easy to add using a new attribute on <script> since the parser already pauses there, so making something like <script transclude={url}> would likely not be too difficult.
SSI is still a thing: I use it on my personal website. It isn't really part of the HTML, though: it's a server-dependent extension to HTML. It's supported by Apache and nginx, but not by every server, so you have to have control over the server stack, not just access to the documents.
Flash's reputation was quite low at the time and people were ready to finally move on from plugins being required on the web. (Though the "battle" then shifted to open vs. closed codecs.)
From what I remember, the main problem was that it broke URLs: you could only link to the initial state of the page, and navigating around the site wouldn't update the address bar - so deep linking wasn’t possible (early JavaScript SPA frameworks had the same issue, BTW). Another related problem was that each subframe had to be a full HTML document, so they did have their own individual URLs. These would get indexed by search engines, and users could end up on isolated subframe documents without the surrounding context the site creator intended - like just the footer, or the article content without any navigation.
https://miragecraft.com/blog/replacing-html-imports
At the end of the day it’s not something trivial to implement at the HTML spec/parser level.
For relative links, how should the page doing the import handle them?
Do nothing and let it break, convert to absolute links, or remap it as a new relative link?
Should the include be done synchronously or asynchronously?
The big benefit of traditional server side includes is that its synchronous, thus simplifying logic for in-page JavaScript, but all browsers are trying to eliminate synchronous calls for speed, it’s hard to see them agreeing to add a new synchronous bottleneck.
Should it be CORS restricted? If it is then it blocks offline use (file:// protocol) which really kills its utility.
There are a lot of hurdles to it and it’s hard to get people to agree on the exact implementation, it might be best to leave it to JavaScript libraries.
The logic is performed elsewhere. If you were to have includes directly in HTML, it means that browsers must implement logic for HTML. So it is not 'just' a parser anymore.
Imagine for example that I create an infinite loop of includes, who is responsible to limit me? How to ensure that all other browsers implement it in the same way?
What happens if I perform an injection from another website? Then we start to have cors policy management to write. (iframes were bad for this)
Now imagine using Javascript I inject an include somewhere, should the website reload in some way? So we have a dynamic DOM in HTML?
Client-side includes are not "processing". HTML already has frames and iframes which do this, just in a worse way, so we'd be better off.
(yes in my view I interpret includes as a basic procedure)
[1] http://www.info.ucl.ac.be/people/PVR/paradigmsDIAGRAMeng201....
https://en.wikipedia.org/wiki/Transclusion
We can probably copy the specs for <frameset> and deal with it the same way:
https://www.w3.org/TR/WD-frames-970331#:~:text=Infinite%20Re...
> How to ensure that all other browsers implement it in the same way?Browsers that don't implement the specs will eventually break:
https://bugzilla.mozilla.org/show_bug.cgi?id=8065
https://github.com/jasoncartwright/clientsideinclude
Originally, iframe were the solution, like the posts mentions. By the time iframes became unfashionable, nobody was writing HTML with their bare hands anymore. Since then, people use a myriad of other tools and, as also mentioned, they all have a way to fix this.
So the only group who would benefit from a better iframe is the group of people who don't use any tools and write their HTML with their bare hands in 2025. That is an astonishing small group. Even if you use a script to convert markdown files to blog posts, you already fall outside of it.
No-one needs it, so the iframe does not get reinvented.
[0] https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/...
[1] https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/...
I still feel like frames were great for their use case.
Github: https://github.com/franzenzenhofer/html-include-polyfill-ext...
SHOW HN: https://news.ycombinator.com/item?id=43881815
An embedded HTML page:
<object data="snippet.html" width="500" height="200"></object>
https://www.w3schools.com/tags/tag_object.asp
[edit: I'm sure there are still some file:// workflows for docs - and yes this doesn't address that]
:)
[0]: https://www.gnu.org/software/emacs/manual/html_node/emacs/in...
[1]: https://emacsdocs.org/docs/emacs/The-Emacs-Editor
https://en.wikipedia.org/wiki/Server_Side_Includes
I have built several sites with pure HTML+CSS, sprinkled with some light SSI with Caddy, and it is rock solid and very performant!
It was not in the early spec, and seems someone powerful wouldn't allow it in later. So everyone else made work arounds, in any way they could. Resulting in the need being lessened quite a bit.
My current best workaround is the <object data=".."> tag, which has a few better defaults than iframe. If you put a link to the same stylesheet in the include file it will match pretty well. Size with width=100%, though with height you'll need to eyeball or use javascript.
Or, Javascript can also hoist the elements to the document level if you really need. Sample code at this site: https://www.filamentgroup.com/lab/html-includes/
It wouldn't make sense to transclude the article about the United States in the article about Wyoming (and in fact modern wikipedia shows a pop up bubble doing a partial transclusion, but would benefit in no way from basic html transclusion.)
It's a simple idea. But of course modern HTML is not at all what HTML was designed to be, but that's the canonical answer.
The elders of HTML would just tell you to make an <a> link to whatever you wanted to transclude instead. Be it a "footer/header/table of contents" or another encylcopdic article, or whatever. Because that's how HTML works, and not the way you suggest.
Think of what would happen if it were the case, you would transclude page A, which transcludes page B, and so with page C, possibly recursively transcluding page B and so. You would transform the User Agent (browser) into a whole WWW crawler!
It's because HTML is pass by reference, not pass by copy.
And it is a genuinely good question!
I think the answer of PD says feels the truest.
JS/CSS with all its bureaucracy are nothing compared to HTML it seems. Maybe people don't find nothing wrong with Html, maybe if they do, they just reach out for js/css and try to fix html (ahem frontend frameworks).
That being said, I have just regurgitated what PD says has said and I give him full credit of that but I am also genuinely confused as to why I have heard that JS / CSS are bureaucratic (I remember that there was this fireship video of types being added in JS and I think I had watched it atleast 1 year ago (can be wrong) but I haven't heard anything for it and I see a lot of JS proposals just stuck from my observation
And yet HTML is such level of bureaucratic that the answer to why HTML doesn't have a feature is because of its bureaucracy. Maybe someone can explain the history of it and why?
This post does link to a technique (new to me) to extract iframe contents:
[0]: https://www.filamentgroup.com/lab/html-includes/
You can do some really silly maneuvers with `window.postMessage` to communicate an expected size between the parent and frame on resize, but that's expensive and fiddly.
The host can then act as a server for the iframe client, even updating it's state or DOM in response to a message from the iframe.
Asking for things that the W3C had specced out in 2006 for XML tech is just not reasonable if it doesn't facilitate clicks.
> We’ve got <iframe>, which technically is a pure HTML solution, but
And then on the following paragraph..
> But none of the solutions is HTML
> None of these are a straightforward HTML tag
Not sure what the point is. Maybe just complaining
"We’ve got <iframe>, which technically is a pure HTML solution, but they are bad for overall performance, accessibility, and generally extremely awkward here"
customElements.define("include", class extends HTMLElement { connectedCallback() { fetch(this.getAttribute("href")).then(x => x.text()).then(x => this.outerHTML = x) } })