Strange regex match node.js

Question

I have a regular expression in node.js which matches some strange things. Look at this:

var regex = new RegExp('(<\?%)|(%\?>)', 'g');
console.log('<tag><?%text%?></tag>'.match(regex));

Leads to [ '>', '%', '%', '>', '>' ] and I don't understand why.

The purpose was to match <?% or %?> and it works perfectly fine on https://regex101.com/.

score 3 · Accepted Answer · 2016-04-14 18:39:07Z

3

That is because you haven't escaped \. It should be \\.

Press Ctrl + Shift + I , go in Console and paste the following code.

var regex = new RegExp('(<\\?%)|(%\\?>)', 'g');
console.log('<tag><?%text%?></tag>'.match(regex));

edited Apr 14, 2016 at 18:39

answered Apr 14, 2016 at 18:30

user2705585

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4 Comments

user2705585 Over a year ago

@SLaks: Your reason is correct. I was showing why OP's code was not working since `` was unescaped.

brandonscript Over a year ago

That actually does work though... am I missing something @SLaks?

user2705585 Over a year ago

@sweaver2112: Ow the damn typo ! Not in good faculties of vision at this time or day.

Scott Weaver Over a year ago

@remus: i would guess he's saying that a regex literal makes for a smaller, simpler regex without the need to escape the backslash. I'd probably not make such a blanket statement there, however, as noob's solution seems ok to me.

SLaks · Accepted Answer · 2016-04-14 18:30:49Z

2

Your backslashes are being swallowed by string escaping.

You should use a regex literal instead: /(<\?%)|(%\?>)/g

answered Apr 14, 2016 at 18:30

SLaks

891k182 gold badges1.9k silver badges2k bronze badges

2 Comments

user2705585 Over a year ago

Your badges are breaking CSS. Should inform on Meta !

Shafizadeh Over a year ago

Yeah, noob is right, that's like a bug. Also there is another weird thing. SLaks has 500k rep and I never seen him here at all .. Where have you been until now? :-)

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