function readyStateChangeEventListenerDefault(httpRequest, target) {
	if (httpRequest.readyState == 4) {
		if (httpRequest.status == 200) {
			if (httpRequest.responseText.length == 0) {
	   			target.innerHTML = '';
				document.getElementById('selectSubCat').value = 'sub-categoria';		
			}
			else {
	   			target.innerHTML = httpRequest.responseText;
			}
	    } 
	    else {
			alert(httpRequest.responseText);
		}
	} 
	else {
	}
}

function getAJAXChannel(target) {
	var httpRequest;
	if (window.XMLHttpRequest) { // Mozilla, Safari, ...
		httpRequest = new XMLHttpRequest();
	} 
	else if (window.ActiveXObject) { // IE
		try {
        	httpRequest = new ActiveXObject("Msxml2.XMLHTTP");
        } 
        catch(e)   {
			try {
				httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
			} 
			catch (e2)   {
			}
		}
	}
	httpRequest.onreadystatechange = function() {
		readyStateChangeEventListenerDefault(httpRequest, target);
	};
	return httpRequest;
}

function listSubCategory(targetURL, childContainerID) {
	
	var childContainer = document.getElementById(childContainerID);
	var httpRequest = getAJAXChannel(childContainer);
	
	httpRequest.open('GET', targetURL, true);
	httpRequest.send(null);
}