/*
	Standards Compliant Rollover Script
	Author : Daniel Nolan
	http://www.bleedingego.co.uk/webdev.php
	
	Add the attribute class="imgover" to any image in your document that requires a mouseover effect to be trigger
    Hover image is named exactly the same as the original image plus _o at the end of name
*/

function initRollovers() {
	if (!document.getElementById) return
	
	var aPreLoad = new Array();
	var sTempSrc;
	var aImages = document.getElementsByTagName('img');

	for (var i = 0; i < aImages.length; i++) {		
	
		//there may be multiple class assignments
		//separates the img class into an array
		classes = aImages[i].className.split(" ");
				
		//checks if img has a class of menu
		//if so, set up rollover
		if ( inArray('imgover', classes) ) {

			var src = aImages[i].getAttribute('src');
			var ftype = src.substring(src.lastIndexOf('.'), src.length);
			var hsrc = src.replace(ftype, '_on'+ftype);

			aImages[i].setAttribute('hsrc', hsrc);
			
			aPreLoad[i] = new Image();
			aPreLoad[i].src = hsrc;
			
			aImages[i].onmouseover = function() {
				sTempSrc = this.getAttribute('src');
				this.setAttribute('src', this.getAttribute('hsrc'));
			}	
			
			aImages[i].onmouseout = function() {
				if (!sTempSrc) sTempSrc = this.getAttribute('src').replace('_on'+ftype, ftype);
				this.setAttribute('src', sTempSrc);
			}
		}
	}
}

function inArray( value, array ) {
//passed a value and an array, this function returns true
//if the value is contained with in the array,
//false if it is not

	for ( var i = 0; i < array.length; i++ )
		if ( array[i] == value )
			return true;
	return false;
} 

//adds functions to the windows onload event
function addOnload(newFunction) {
  var oldOnload = window.onload;
    // does window.onload exist
  if (typeof oldOnload == "function") {
            //overwriting existing onload
              window.onload = function() {
                  if (oldOnload) {oldOnload();}
                  newFunction();
              }
          }
          else {
              window.onload = newFunction;
          }
} 

addOnload(initRollovers);