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My RegEx is screwing up the rest of my javascript...

Answer 1

+3 A:

match() returns an array, not a string, so at a minimum you need something like this:

url_param = $(this).attr("href").match(/show:[^/]+/i);
if (url_param && url_param.length > 0) {
    show_number = url_param[0].substr(5);
    alert(show_number);
}

A neater way to get the piece of the URL after the "show:" is to use parentheses to capture that part of the URL, which will end up in url_param[1]:

url_param = $(this).attr("href").match(/show:([^/]+)/i);
if (url_param && url_param.length > 0) {
    show_number = url_param[1];
    alert(show_number);
}

RichieHindle 2009-06-23 00:46:31

You should also make sure url_param is not null. If the match fails, it returns null, not an empty array. In this case checking for null is sufficient even, because the RegExp requires the captured group.

Matthew Crumley 2009-06-23 07:24:54

@Matthew: Good point; now fixed. Thanks!

RichieHindle 2009-06-23 08:00:25

Answer 2

A:

I think the problem is that the JavaScript interpreter cannot parse your code. Your regex:

/show:[^/]+/i

Should be:

/show:[^\/]+/i

because the forward slash is prematurely ending your regex. To verify this, you should view whatever JavaScript error console your browser provides to see if you're getting a JavaScript error.

Jacob 2009-06-23 00:50:11

@Jacob: It works fine for me as it is (which I believe is correct, because a forward slash within a character class shouldn't terminate the regex) but a backslash can't hurt.

RichieHindle 2009-06-23 00:54:09

Answer 3

A:

No, the problem is not with the backslash. Jacob is correct, it does not need quoting.

The problem is that indeed, match returns an array. Hence the following simple test case does NOT work.

<html>
<script type="text/javascript">
var a='show: something';
url_param = a.match(/show:[^/]+/i);
show_number = url_param.substring(5);
alert (show_number);
</script>
</html>

However, this second version DOES work.

<html>
<script type="text/javascript">
var a='show: something';
url_param = a.match(/show:[^/]+/i);
show_number = url_param[0].substring(5);
alert (show_number);
</script>
</html>

Even better is probably something explicit which handles whitespace, checks for start and end of string, and does a pattern match extraction.

<html>
<script type="text/javascript">
var a='show: something';
url_param = a.match(/^\s*show:\s*([^/]+)\s*$/i);
show_number = url_param[0].substring(5);
alert (show_number);
</script>
</html>

That's a bit more bullet-proof.

the.jxc 2009-06-23 04:51:07

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My RegEx is screwing up the rest of my javascript...

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