Javascript is freezing the browser when running this code

Question

I am trying to get the value of a text input and check if there is any links in it and then take those links and make them into tags. But when I run this code, something is going wrong and it completely freezes the page. Basically, I want it to check for "http://" and if that exists, to keep on adding to the substr length until the end of the string/link. Is there a better way to do this?

// the id "post" could possibly say: "Hey, check this out! http://facebook.com"
// I'd like it to just get that link and that's all I need help with, just to get the      
// value of that entire string/link.
var x = document.getElementById("post");
var m = x.value.indexOf("http://");
var a = 0;
var q = m;

if (m != -1) {
    while (x.value.substr(q, 1) != " ") {
        var h = x.value.substr(m, a);
        q++;
    }
}

It's freezing because you've almost certainly got the potential for an infinite loop. — Lee Taylor
– Lee Taylor, Commented Oct 26, 2012 at 22:45
Also, your variables have terrible names. Code should be able to be looked at and roughly understood. This is not the case here. — Lee Taylor
– Lee Taylor, Commented Oct 26, 2012 at 22:47
The value of q never changes, so your loop condition never changes either, thus infinite loop. — didierc
– didierc, Commented Oct 26, 2012 at 22:48

J. K. · Accepted Answer · 2012-10-27 11:18:32Z

3

Of course it is – there is an infinite loop.

You probably wanted to update the variable q in each iteration.

q = q + a;

or just q += a;

Update:

I see you changed the code a bit.

I get what you're trying to do. You're trying to get a URL from an input value.

Why don't you just use a simple RegExp instead of this unclear loop?

var match = x.value.match(/(?:^|\s)(http:\/\/\S+)/i);
var url = match ? match[1] : null;

edited Oct 27, 2012 at 11:18

answered Oct 26, 2012 at 22:46

J. K.

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1 Comment

Zachrip Over a year ago

I just tried that, I am trying the link http :// facebook.com, it doesn't seem to work correctly. You can try if you want: zach.muny.us/widgets/youtube It appears to only go one letter after http://

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