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I had opened my browser setting and blocked Javascript for all websites. But when I tried to access Facebook, it says "We're sorry, but Facebook doesn't work properly without JavaScript enabled." My question is, how they have detected that my browser is not allowing Javascript?

Khokon M.
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  • Why does it matter how *Facebook, in particular,* does this? – Quentin Mar 17 '19 at 12:24
  • This question is not about programming and therefore doesn't belongs to this site. – Pavindu Mar 17 '19 at 12:24
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    Possible duplicate of [How to detect if JavaScript is disabled?](https://stackoverflow.com/questions/121203/how-to-detect-if-javascript-is-disabled) and [How to inform if Javascript is disabled in the browser](https://stackoverflow.com/questions/3262479) – adiga Mar 17 '19 at 12:26
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    Because they know _everything_ about you... – TGrif Mar 17 '19 at 12:29

2 Answers2

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First – you can display this message by default and remove it with JS.

Seconds – there is a HTML <noscript> tag.

WofWca
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They use the noscript element to selectively redirect.

<noscript><meta http-equiv="refresh" content="0; URL=/?_fb_noscript=1" /></noscript><
Quentin
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