Javascript to clean URL's

Javascript noob here. I'm making a greasemonkey to clean URL's:
http://pastebin.com/XAbJMenZ

Cleaning up the main page url works, but cleaning links on the page doesn't. What am I doing wrong? (apart from probably everything).

>>7
Anyway, the modifyurl() function does work. Cleaning links on the page doesn't:

// Clean links on the page
var links = document.getElementsByTagName('a');
for (var i = 0; i < links.length; i++) {
    links[i].href = modifyurl(links[i].href);
}