Someone

function foo() {	var doc = document.evaluate("//td[@class='b']", document, null, XPathResult.ANY_TYPE,null);	var iter = doc.iterateNext();	var i = 0;	while (iter) {		if ((i % 2) == 1) {			iter.innerHTML += "<br>test<br>";		}		iter = doc.iterateNext();		i++;	}}foo();