// stripes.js
// zebra striped tables from 'http://www.alistapart.com/articles/zebratables/'

// this function is needed to work around 
// a bug in IE related to element attributes
function hasClass(obj) {
	var result = false;
	if (obj.getAttributeNode("class") != null) {
		result = obj.getAttributeNode("class").value;
	}
	return result;
}   

function stripe(id) {

	// the flag we'll use to keep track of 
	// whether the current row is odd or even
	var even = false;
  
	// if arguments are provided to specify the colours
	// of the even & odd rows, then use the them;
	// otherwise use the following defaults:
	var evenColor = arguments[1] ? arguments[1] : "#FFFFFF"; // white
	var oddColor = arguments[2] ? arguments[2] : "#E0EEEE"; // lightcyan
  
	// obtain a reference to the desired table
	// if no such table exists, abort
	var table = document.getElementById(id);
	if (! table) { return; }
	
	// by definition, tables can have more than one tbody
	// element, so we'll have to get the list of child
	// <tbody>s 
	var tbodies = table.getElementsByTagName("tbody");

	// and iterate through them...
	for (var h = 0; h < tbodies.length; h++) {
	
		// find all the &lt;tr&gt; elements... 
		var trs = tbodies[h].getElementsByTagName("tr");
	 
		// ... and iterate through them
		for (var i = 0; i < trs.length; i++) {

			// avoid rows that have a class attribute
			// or backgroundColor style
			if (! hasClass(trs[i]) && ! trs[i].style.backgroundColor) {
 		  
				// get all the cells in this row...
				var tds = trs[i].getElementsByTagName("td");

				// and iterate through them...
				for (var j = 0; j < tds.length; j++) {

					var mytd = tds[j];

					// avoid cells that have a class attribute
					// or backgroundColor style
					if (! hasClass(mytd) && ! mytd.style.backgroundColor) {

						mytd.style.backgroundColor = even ? evenColor : oddColor;

					}
				}
			}
			// flip from odd to even, or vice-versa
			even =  ! even;
		}
	}
}