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up vote 1 down vote favorite

I have several strings in an associative array:

    var arr = {
        '============================================': '---------',
        '++++++++++++++++++++++++++++++++++++++++++++': '---------',
        '--------------------------------------------': '---------'
    };

I want to replace occurrences of each key with the corresponding value. What I've come up with is:

    for (var i in arr)
    {
        strX = str.replace(i, arr[i]);

        console.log('arr[\''+i+'\'] is ' + arr[i] + ': ' + strX);
    }

This works, but only on first occurence. If I change the regex to /i/g, the code doesn't work.

for (var i in arr)
{
    strX = str.replace(/i/g, arr[i]);

    console.log('arr[\''+i+'\'] is ' + arr[i] + ': ' + strX);
}

Do you guys know how to work around this?

share|improve this question
    
Don't use for ... in on arrays. As soon as someone touches the array prototype you will be in for a world of hurt. –  cdhowie Aug 16 '11 at 0:30
2  
I don`t want to be evil but array is [], and {} is object. –  Bakudan Aug 16 '11 at 0:31
    
@cdhowie: OP isn't actually using an Array. var arr = {...}. –  user113716 Aug 16 '11 at 0:31
    
This is true. The name arr confused me. :) Still, if someone touches the object prototype, the OP will still have issues. –  cdhowie Aug 16 '11 at 0:32
    
Touching the object prototype has a lot of its own issues though, and if I remember correctly, can't be done in IE at all. –  Ktash Aug 16 '11 at 0:34
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2 Answers

up vote 4 down vote accepted

Instead of 

strX = str.replace(/i/g, arr[i]);

you want to do something like.

strX = str.replace(new RegExp(i, "g"), arr[i]);

This is because /i/g refers to the letter i, not the value of variable i. HOWEVER one of your base string has plus signs, which is a metacharacter in regexes. These have to be escaped. The quickest hack is as follows:

new RegExp(i.replace(/\+/g, "\\+"), "g"), arr[i]);

Here is a working example: http://jsfiddle.net/mFj2f/

In general, though, one should check for all the metacharacters, I think.

share|improve this answer
2  
There'll actually be an issue with the '++++++++' one since + needs to be escaped. –  user113716 Aug 16 '11 at 0:35
1  
Sadly there is no builtin way to escape special regex chars :( –  user166390 Aug 16 '11 at 0:39
    
Darn, no \Q, \E or Pattern.quote, r'...' or %r{...} in JS.... I'm still looking, though. I'll find something for the OP unless someone beats me to it. :-) –  Ray Toal Aug 16 '11 at 0:45
3  
I think you may need to do an .indexOf() test for +, then do a .replace(/\+/g,'\\+'). –  user113716 Aug 16 '11 at 0:48
1  
Thanks for the commentary, pst and patrick. I was a little confused why the fiddle was not working at first! +1 to patrick and pst. –  Ray Toal Aug 16 '11 at 0:52
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up vote 2 down vote

The i in the regex will be the string i, not the variable i. Try instead new RegExp(i,'g'); and you should get the desired results

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