Javascript For...in Seems To Only Return Every Other Index In Array

I have a page (actually, about thirty or so) where I'm trying to change the classname of specific elements based on a querystring variable. Everything works fine except for this pa

Solution 1:

Šime Vidas pointed out that getElementsByClassName retuns a live nodeList, meaning the collection stored will be updated as things are changed (here the class attribute).

var hitAreas = document.getElementsByClassName('hitArea'),
    hitAreasLength = hitAreas.length;

while ( hitAreasLength-- > 0) {
    hitAreas[hitAreasLength].className = 'hitArea_practice';
}

I'm not sure if this is the nicest code, but it works :)

jsFiddle.