[j0hnik]

Янковиц,
примеров в сети уйма

var request = new XMLHttpRequest();
request.open('GET', '/my/url', true);

request.onload = function() {
	if (this.status >= 200 && this.status < 400) {
		// Success!
		var resp = this.response;
	} else {
		// We reached our target server, but it returned an error
	}
};
request.onerror = function() {
	// There was a connection error of some sort
};
request.send();