var tables = getElementsByClassName("tables");

for(var i = 0,ii = tables.length; i < ii; i++) {
	var tbodys = tables[i].getElementsByTagName("tbody");

	for(var j = 0,jj = tbodys.length; j < jj; j++) {
		var rows=tbodys[j].getElementsByTagName("tr");

		for(var k = 1, kk = rows.length; k < kk; k += 2) {
			rows[k].className = "alt"
		}
	}
}

function getElementsByClassName(className) {
	if(document.all) {
		var allElements = document.all
	} else {
		var allElements = document.getElementsByTagName("*")
	}

	var foundElements = [];

	for(var i = 0,ii = allElements.length; i<ii; i++) {
		if(allElements[i].className == className) {
			foundElements[foundElements.length] = allElements[i]
		}
	}

	return foundElements
}