Why do websites prevent pasting via onpaste="return false;"

4 gleenn 1 5/8/2025, 9:37:17 PM

Why do websites do this? Isn't it trivial for bots etc to easily side-step any protection this might give? Or is it just to make people "double-check" their inputs? I find it completely maddening because I would assume I'm way more likely to correctly input a copy-pasted e.g. routing or account number than if I have to manually enter anything. Can we just agree this is terrible UI and is probably detrimental to correct data entry? What am I missing? In frustration I even sometimes open the dev tools and remove this attribute on elements out of spite.

Comments (1)

pwg · 3h ago

> Can we just agree this is terrible UI

It is, but they had some "checklist" that included "block paste" for reasons unknown, and so they blocked pasting.

In firefox, if you change the about:config setting "dom.event.clipboardevents.enabled" to false you'll be able to paste no matter whether the website operator has "block paste" on their braindead checklist or not.

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Why do websites prevent pasting via onpaste="return false;"

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