var xhr = new XMLHttpRequest();
xhr.open("POST", '/url', true);
xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
xhr.onreadystatechange = function() { // Call a function when the state changes. if (this.readyState === XMLHttpRequest.DONE && this.status === 200) { // Request finished. Do processing here. }
}
xhr.send("name=Hello&id=world");

var xhr = new XMLHttpRequest();
var params = 'field1='+postfield1+'&field2='+postfield2;
xhr.open('POST', 'http://exmaple.com', true);
//Send the proper header information along with the request
xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
xhr.onload = function() {//Call a function when the state changes. if(xhr.status == 200) { alert(this.responseText); }
}
xhr.send(params);