Using Variable inside pregmatch in js

Question

I have the following orginal code of preg match

for(var i = 0;i<5;i++)
{ 
patt1 = /Colour1\/(\d+)"/; 
var ab=(data.match(patt1)[1]); 
alert(ab);
}

I am wondering if i can use the variable i instead of 1(for 5 loops),like below example.I can use the value i outside but not inside pregmatch.

 for(var i = 0;i<5;i++)
{<br>
patt1 = /Colour"+i+"\/(\d+)"/; 
var ab=(data.match(patt1)[1]); 
alert(ab);
}

This should answer your question: http://stackoverflow.com/questions/494035/how-do-you-pass-a-variable-to-a-regular-expression-javascript — travega, Jan 25 '12 at 19:42

Joseph Silber · Answer 1 · 2012-01-25T19:54:57.590

1

You'll have to use the RegExp constructor:

for (var i = 0; i < 5; i++)
{
    var patt1 = new RegExp('Colour' + i + '/(\\d+)"'),
        ab = (data.match(patt1) || [])[1]; 
    alert(ab);
}

Remember to double escape your slashes!

edited Jan 25 '12 at 19:54

answered Jan 25 '12 at 19:41

Joseph Silber

You forgot to double up on the backslashes – hugomg Jan 25 '12 at 19:45
I don't think you need to escape slashes if you're not using `/regex/` notation. – Michael Krelin - hacker Jan 25 '12 at 19:50

Michael Krelin - hacker · Answer 2 · 2012-01-25T19:48:45.640

1

Like this?

var ab = data.match('Colour'+i+'/(\\d+)"')[1];

edited Jan 25 '12 at 19:48

answered Jan 25 '12 at 19:42

score 1 · Answer 3 · 2012-01-25T19:51:44.553

1

Sure

patt1 = new RegExp("Colour"+i+"/(\\d+)\"");

but you could also skip the loop

patt1 = new RegExp("Colour[0-4]/(\\d+)\"");

edited Jan 25 '12 at 19:51

answered Jan 25 '12 at 19:42

@JustinBiaber: You're welcome. I just updated it to require the closing `"` in the regex. If that's not needed, remove the `\"`. – Jan 25 '12 at 19:52

3 Answers3