How to pass a variable into regex in jQuery/Javascript

Question

3

Is there a way to pass a variable into a regex in jQuery/Javascript?

I wanna do something like:

var variable_regex = "bar";
var some_string = "foobar";

some_string.match(/variable_regex/);

In Ruby you would be able to do:

some_string.match(/#{variable_regex}/)

Found a useful post:

asked Nov 8 '09 at 7:09

Kinopiko · Answer 1 · 2009-11-08 07:39:27Z

3

It's easy:

var variable_regex = "bar";
var some_string = "foobar";

some_string.match(variable_regex);

Just lose the //. If you want to use complex regexes, you can use string concatenation:

var variable_regex = "b.";
var some_string = "foobar";

alert (some_string.match("f.*"+variable_regex));

answered Nov 8 '09 at 7:23

Kinopiko
8,1281831

	I don't know why I didn't see this. Thanks. – cinematic Nov 8 '09 at 7:28
	I had a complex regex and I wanted to interpolate a variable pattern into a hardcoded expression, but I guess I'd just set each regex permutation to a whole variable. – cinematic Nov 8 '09 at 7:31

Jonathan Lonowski · Answer 2 · 2009-11-08 07:17:10Z

2

Javascript doesn't support interpolation like Ruby -- you have to use the RegExp constructor:

var aString = "foobar";
var pattern = "bar";

var matches = aString.match(new RegExp(pattern));

answered Nov 8 '09 at 7:17

Thanks, this is what I was looking for. – cinematic Nov 8 '09 at 7:25

2 Answers