How to use JavaScript regex over multiple lines?

Question

var ss= "<pre>aaaa
bbb
ccc</pre>ddd";
var arr= ss.match( /<pre.*?</pre>/gm );
alert(arr);     // null

I'd want the PRE block be picked up, even though it spans over newline characters. I thought the 'm' flag does it. Does not.

Found the answer here before posting. SInce I thought I knew JavaScript (read three books, worked hours) and there wasn't an existing solution at SO, I'll dare to post anyways. throw stones here

So the solution is:

var ss= "<pre>aaaa
bbb
ccc</pre>ddd";
var arr= ss.match( /<pre[sS]*?</pre>/gm );
alert(arr);     // <pre>...</pre> :)

Does anyone have a less cryptic way?

Edit: this is a duplicate but since it's harder to find than mine, I don't remove.

It proposes [^] as a "multiline dot". What I still don't understand is why [. ] does not work. Guess this is one of the sad parts of JavaScript..

Answer 1

DON'T use (.|[ ]) instead of . for multiline matching.

DO use [sS] instead of . for multiline matching

Also, avoid greediness where not needed by using *? or +? quantifier instead of * or +. This can have a huge performance impact.

See the benchmark I have made: http://jsperf.com/javascript-multiline-regexp-workarounds

Using [^]: fastest
Using [sS]: 0.83% slower
Using (.|
|
): 96% slower
Using (.|[
]): 96% slower

NB: You can also use [^] but it is deprecated in the below comment.