// JavaScript Document
/* This script and many more are available free online at
The JavaScript Source!! http://javascript.internet.com
Created by: Bobby van der Sluis | http://www.bobbyvandersluis.com/ */
// Details can be found at:
// http://www.bobbyvandersluis.com/articles/unobtrusivedynamicselect.php
function dynamicSelect(id1, id2) {
	// Browser and feature tests to see if there is enough W3C DOM support
	var agt = navigator.userAgent.toLowerCase();
	var is_ie = ((agt.indexOf("msie") != -1) && (agt.indexOf("opera") == -1));
	var is_mac = (agt.indexOf("mac") != -1);
	if (!(is_ie && is_mac) && document.getElementById && document.getElementsByTagName) {
		// Obtain references to both select boxes
		var sel1 = document.getElementById(id1);
		var sel2 = document.getElementById(id2);
		// Clone the dynamic select box
		var clone = sel2.cloneNode(true);
		// Obtain references to all cloned options
		var clonedOptions = clone.getElementsByTagName("option");
		// Onload init: call a generic function to display the related options in the dynamic select box
		refreshDynamicSelectOptions(sel1, sel2, clonedOptions);
		// Onchange of the main select box: call a generic function to display the related options in the dynamic select box
		sel1.onchange = function() {
			refreshDynamicSelectOptions(sel1, sel2, clonedOptions);
		};
	}
}

function refreshDynamicSelectOptions(sel1, sel2, clonedOptions) {
	// Delete all options of the dynamic select box
	while (sel2.options.length) {
		sel2.remove(0);
	}
	// Create regular expression objects for "select" and the value of the selected option of the main select box as class names
	var pattern1 = /( |^)(select)( |$)/;
	var pattern2 = new RegExp("( |^)(" + sel1.options[sel1.selectedIndex].value + ")( |$)");
	// Iterate through all cloned options
	for (var i = 0; i < clonedOptions.length; i++) {
		// If the classname of a cloned option either equals "select" or equals the value of the selected option of the main select box
		if (clonedOptions[i].className.match(pattern1) || clonedOptions[i].className.match(pattern2)) {
			// Clone the option from the hidden option pool and append it to the dynamic select box
			sel2.appendChild(clonedOptions[i].cloneNode(true));
		}
	}
}


// Multiple onload function created by: Simon Willison
// http://simon.incutio.com/archive/2004/05/26/addLoadEvent
function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}