Add hasAttribute, indexOf methods to IE in Javascript

IE does not have the hasAttribute method, but it provides getAttribute, which requires you to do it yourself, so that hasAttribute will be taken over in FF/IE

function hasAttribute(elm, attribute){
return elm.getAttribute(attribute) != null;
}

The default method of Array in Javascript does not provide the indexOf method, so you can add it yourself.
BTW: It’s really cool to use prototype to Hack Javascript

if (!Array.prototype.indexOf) Array.prototype.indexOf = function(item, i) {
i || (i = 0);
var length = this.length;
if (i < 0) i = length + i;
for (; i < length; i++)
if (this[i] === item) return i;
return -1;
};