Have HTML5's a inputs pattern attribute ignore case

Question

I need to have HTML's input elements pattern ignore the case of the value,
like have if the regex is /[a-z]*/ could I get it to match all uppercase letters too?
(I know I could just do /[a-zA-Z]*/, but that was an example.)

score 76 · Accepted Answer · edited May 21 '18 at 10:23

76

I don't think it is possible.

The specification on <input pattern> [1,2] specifies that
- the pattern uses the ECMAScript (i.e. Javascript) flavor of regex
- it is compiled "with the global, ignoreCase, and multiline flags disabled"
In Javascript, the only way to make a regex ignore case is to set the modifier externally (/.../i). The PCRE syntax (?i) is not supported.

Therefore, the pattern is always case-sensitive and [a-zA-Z]* (i.e. making the regex itself explicitly case insensitive) is the only way to match the pattern in a case-insensitive way.

edited May 21 '18 at 10:23

mikemaccana

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answered Apr 02 '11 at 18:42

kennytm

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@dominicbri7 "with [...] flags ***disabled***". If the flag to ignore case is disabled, then it doesn't ignore case, so it's case sensitive. – Niet the Dark Absol Jun 10 '14 at 15:37
Great answer. (The pedant on my shoulder would have preferred you to have written 'verbosely' or 'explicitly' instead of 'manually' but it doesn't stop your answer being helpful) – Martin Joiner Dec 10 '17 at 15:00
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so inconvenient when it comes to matching multiple terms in a case insensitive manner – oldboy Dec 26 '20 at 08:19
[sS][uU][cC][kK][sS]\. – King Friday May 03 '23 at 22:50
...though I can't find where documentation claims they are disabled... – massic80 Jun 22 '23 at 08:23

Have HTML5's a inputs pattern attribute ignore case

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