Retrieving parameter of a function using regular expressions in javascript

Question

for example if we consider document.createElement() function the parameter can be passed in 3 ways

var v="script"; var s=document.createElement(v);

var s=document.createElement("script");

var s=document.createElement('scipt');

i want a regular expression which extracts the parameter in document.createElement function excluding quotes. I tried this by using groups but i am writing two regular expression one for "",'' and other for normal variable please provide an example

You're going to parse JavaScript code with regexes?! Better wrap document.createElement to make hook. Also, script may be inserted via document.body.innerHTML += "<script type='text/javascript'></script>". — kirilloid
– kirilloid, Commented Apr 4, 2012 at 7:37
what does that mean wrapping document.createElement? please explain — user1275375
– user1275375, Commented Apr 4, 2012 at 8:14
var f = document.createElement; document.createElement = function(tagName){ console.log(tagName); f.apply(document, arguments); } This code is tracking document.createElement calls dynamically, though. I.e. One cannot say about some code which tags are created beforehead. — kirilloid
– kirilloid, Commented Apr 4, 2012 at 8:18
thank you so much can you provide any tutorial which clearly explains this concept — user1275375
– user1275375, Commented Apr 4, 2012 at 8:44

mihai · Accepted Answer · 2012-04-04 08:08:01Z

1

var re = /document\.createElement\((['"]*)(.+?)\1\)/;

The result is in:

str.match(re)[2];

http://jsfiddle.net/mihaifm/RWc8N/

answered Apr 4, 2012 at 8:08

mihai

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3 Comments

user1275375 Over a year ago

This does not match var s=document.createElement(v);

user1275375 Over a year ago

it is not working because in the above code v is not in double quotes or single quotes.

mihai Over a year ago

did you check the example? I have return the correct result for all 3 cases...I'm not sure what you mean in your comment

Ofer Zelig · Accepted Answer · 2012-04-04 07:39:49Z

0

Use pipe - | for OR operations.

For example: script|scipt.

answered Apr 4, 2012 at 7:39

Ofer Zelig

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