By far the most common technique used, XMLHttpRequest (XHR) allows you to asyn- chronously send and receive data.

req.responseText.js

var url = '/data.php';
var params = [
 'id=934875',
 'limit=20'
];
var req = new XMLHttpRequest();
req.onreadystatechange = function() {
 if (req.readyState === 4) {
 var responseHeaders = req.getAllResponseHeaders(); // Get the response
headers.
 var data = req.responseText; // Get the data.
 // Process the data here...
 }
}
req.open('GET', url + '?' + params.join('&'), true);
req.setRequestHeader('X-Requested-With', 'XMLHttpRequest'); // Set a request
header.
req.send(null); // Send the request.