Regex to detect when certain characters or substrings

Question

I'm currently using a regex to detect space, single-quote & double-quote in an input.

I would like to add the detection of several strings: ex. 'xxx' & 'yyy'. It should only detect for those complete strings, so 'x' or 'y' by itself wouldn't be detected.

Currently have this in html input code:

<input type="text" pattern="^(?=.*[\x27\x20\x22]).+$" ...

@WiktorStribiżew I tried it - the xxx & yyy is working but now the space/'/" isn't working. — Jay
– Jay, Commented Jan 26, 2019 at 23:16

Jay · Accepted Answer · 2019-01-28 20:36:26Z

1

If you just want to ensure exactly one space, single-quote or double-quote appears in the input, you can simplify your pattern to:

<input type="text" pattern="[\x27\x20\x22]" ...

To detect other things, you can add "alternations", separated by |:

<input type="text" pattern="[\x27\x20\x22]|xxx|yyy" ...

As per jhnc: To detect any instance, no matter where in the string:

<input type="text" pattern=".*([\x27\x20\x22]|xxx|yyy).*" ...

edited Jan 28, 2019 at 20:36

Jay

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answered Jan 26, 2019 at 23:15

jhnc

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5 Comments

Jay Over a year ago

Sorry to bother you, but I tried your pattern and it's not working - I've set up a jsfiddle - hopefully you can tell me what's wrong. Test by changing value="" to something jsfiddle.net/billparti/x0t7k5sn

jhnc Over a year ago

What are you expecting to happen? If I delete the value="xxx" and all the CSS, run, and just type into the textbox, I see the expected browser highlighting.

jhnc Over a year ago

By the way, if you want to match something like "hello xxx.123" and not precisely " " or "xxx", etc, then you will need to put back the .* at the start and end: eg. pattern=".*([\x27\x20\x22]|xxx|yyy).*" as patterns are implicitly wrapped with ^ and $

jhnc Over a year ago

If you mean that "Pattern Match" is never displayed, it's because the .warn div is not a child of input. Try changing the css selector to ... ~ .warn or ... + .warn or somesuch. cf. w3schools.com/cssref/css_selectors.asp

Jay Over a year ago

Yep, I needed the additional code ( the third suggestion) is now the accepted answer - thanks

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