// Adapted from code published at:
// 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) {
	var even = false;	// the flag we'll use to keep track of whether the current row is odd or even
	
	// if arguments are provided to specify the colours
	// of the even & odd rows, then use the them;
	// otherwise use the following defaults:
	var highRowBackgroundColor = arguments[1] ? arguments[1] : "#ffffcc";
	
	// 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++) {
		var trs = tbodies[h].getElementsByTagName("tr");	// find all tr elements
		for (var i = 0; i < trs.length; i++) {	// iterate through rows
			// avoid rows that have a class attribute
			// or backgroundColor style
			if (! hasClass(trs[i]) && ! trs[i].style.backgroundColor && even ) {
				trs[i].style.backgroundColor = highRowBackgroundColor;
			}
			even =  ! even;	// flip from odd to even, or vice-versa
		}
	}
}