function ch(obj, tag, u) { 
		for(var re=[], i=0, nodes = obj.childNodes; i < nodes.length; i++) (tag!=u && tag.toUpperCase()==nodes[i].tagName)?re.push(nodes[i]):(tag==u)?re.push(nodes[i]):null;
		return re;
	}
	
	console.log(ch(document.getElementById('saaa'), 'input'));