JavaScript regular expression returns false, but regex tester returning true

Question

I have a JavaScript regular expression that I'm using for frontend password validation in an input field. Here is what my input field looks like:

<input type='password' placeholder='Password...' id='password' pattern='^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[!@#\$%\^&\*])(?=.{8,})' required>

That regular expression is looking for a string: eight characters or longer, with an uppercase letter, lowercase letter, number, and a special character. Let's take the string: November2017! for instance. That should pass the regular expression, but it doesn't in my webapp. And when I copy and paste the regular expression from my input field ^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[!@#\$%\^&\*])(?=.{8,}) and put it into regex101.com, that string passes the validation. But it does not pass the validation in my webapp. Is there a specific reason why putting it in a pattern attribute would change whether or not it would pass validation?

Regex isn't 100% standardized, are you sure the regex tester was set to JavaScript's regex? — Gry-
– Gry-, Commented Nov 15, 2017 at 2:57
pattern requires to match the complete string. Your pattern does not match the complete string regex101.com/r/WcqXSR/1 It matches the position in the beginning of the string only. — zerkms
– zerkms, Commented Nov 15, 2017 at 3:01

zerkms · Accepted Answer · 2017-11-15 03:02:29Z

2

You need to add the .{8,} in the end.

^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[!@#\$%\^&\*]).{8,}

It happens because the pattern must match the complete string, and your current expression only matches the beginning of the string.

answered Nov 15, 2017 at 3:02

zerkms

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