var http_request = false;

function makePOSTRequest(url, parameters, resultRequest ) {
	http_request = false;
	if (window.XMLHttpRequest) { // Mozilla, Safari,...
		http_request = new XMLHttpRequest();
		if (http_request.overrideMimeType) {
			http_request.overrideMimeType('text/html');
		}
		} else if (window.ActiveXObject) { // IE
			try {
					http_request = new ActiveXObject("Msxml2.XMLHTTP");
				} catch (e) {
				try {
					http_request = new ActiveXObject("Microsoft.XMLHTTP");
				} catch (e) {}
		}
	}
	if (!http_request) {
		alert('Essa menssagem não pode ser enviada por esse navegador');
		return false;
	}
  
	http_request.onreadystatechange = resultRequest;
	http_request.open('POST', url, true);
	http_request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	http_request.setRequestHeader("Content-length", parameters.length);
	http_request.setRequestHeader("Connection", "close");
	http_request.send(parameters);
}