Loops in GreaseMonkey

I'm developing my first greasemonkey script (trying to edit and add page content to a particular website) and for some reason, it refuses to work beyond one while loop.. Eg :

var anchorTag = window.document.getElementsByTagName('a');
var anchorTagNumber = window.document.getElementsByTagName('a').length;
..
..
i = 0
j = 0;
function collectId(i,link) {
    linkArray[j] = new Array(2);
    linkArray[j][0] = i;
    linkArray[j][1] = link;
    j++;
}


while(i <= anchorTagNumber)
{
    testHref = anchorTag[i].href;
    testHTML = anchorTag[i]开发者_开发技巧.innerHTML;
    patHref = /some regex/;
    patCaptureId = /some regex/;
    testId = patCaptureId.exec(testHref);
    patHTML = /some regex/;
    patHTML2 = /some regex/;
    patHTML3 = /some regex/;
    if(patHref.test(testHref) && !patHTML.test(testHTML) && !patHTML2.test(testHTML))
    {
        linkId = testId[1];
        collectId(i,linkId);
    }
    i++;
}

Anything after this while loop ends, refuses to work. Even a simple alert doesn't seem to execute. I have another while loop with a similar structure, and if I put that one first, it executes and this one doesn't. Any Ideas ? Thanks in advance !

The most obvious problem is that the array is being overrun, which will cause the script to error-out.

This: while(i <= anchorTagNumber)
Should be: while(i < anchorTagNumber).
If an array has length 5, for example, its last element will have an index of 4.

Also, this:

var anchorTag = window.document.getElementsByTagName('a');
var anchorTagNumber = window.document.getElementsByTagName('a').length;

Can be simplified to:

var anchorTag       = window.document.getElementsByTagName('a');
var anchorTagNumber = anchorTag.length;

That will speed the code slightly but also makes future code maintenance, or reuse, easier.

Instead of using a while, you could try a setInterval to call you function every 100 miliseconds.

interval = setInterval(function(){
    iDidIt = doSomethin()
    if(iDidIt){
       clear interval;
    }
},100)