Regex - PHP to Javascript

Question

I have the following regex:

<div\s*class="selectionDescription">(.*?)<\/div>

Which works with PHP perfectly. I am aware that javascript does not support the \s flag.

I have tried using the \g flag, however my pattern is not matched.

I am looking to match everything inside the div in the following string:

<div class="selectionDescription">Text to match</div>

I receive the following error in javascript:

Uncaught SyntaxError: Invalid flags supplied to RegExp constructor 's'(…)

Uncaught SyntaxError: Invalid flags supplied to RegExp constructor 's'(…) — CMS
– CMS, Commented Feb 19, 2016 at 17:36
Your pattern seems to work. What is the problem you're seeing? — xyhhx
– xyhhx, Commented Feb 19, 2016 at 17:36
Why not use use the DOM and do something like document.getElemementsByClassName('selectionDescription')? Where is this string coming from and why are you using a regex on it? — gen_Eric
– gen_Eric, Commented Feb 19, 2016 at 17:36
Can you show us your actual JavaScript code? \g isn't a flag, btw, it's /g. Are you confusing \s (match a whitespace character) with the /s flag (to make . match new lines) or /g ("match all")? — gen_Eric
– gen_Eric, Commented Feb 19, 2016 at 17:37

xyhhx · Accepted Answer · 2016-02-19 17:38:20Z

2

Your pattern seems to work.

s is not a flag, so if you are trying something like new RegExp('<div\s*class="selectionDescription">(.*?)<\/div>', 's') then yes, you would find an error.

You do not need to add any flags, except perhaps the g flag to capture this div many times. (Check it out)

Maybe check out a quick primer on Javascript's regular expressions?

answered Feb 19, 2016 at 17:38

xyhhx

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OnlineCop · Accepted Answer · 2016-02-19 18:11:27Z

If you are spanning multiple lines, and you mean the single line mode that s provides, you can emulate that with [\S\s] or some other similar "all inclusive, all exclusive" style: [\d\D], [\W\w], etc.

That will allow it to span multiple lines and still match:

<div\s*class="selectionDescription">([\S\s]*?)<\/div>

You need to be wary of using lazy *? quantifiers, however. Take a look at https://regex101.com/r/xD2jV8/1 where the number of steps is 220.

If the content between <div> and </div> tags is very large, this becomes very computationally expensive, very fast.

While slightly less readable,

<div\s*class="selectionDescription">((?:[^<]+|<(?!\/div>))*)<\/div>

would do the same but within only 69 steps.

And at that point, https://regex101.com/r/xD2jV8/3 slightly optimizes it further, but HTML really isn't the best way to handle things with HTML. jQuery could perform this quickly and much "safer": $('div.selectionDescription').html()

Of course, you may not have access to this at this point, but HTML is usually not the best thing to use for parsing HTML.

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