This automatic essay grader is a simple example of an Ajax (XMLHttprequest) interaction from Paul Adams’ Ajax for Beginners tutorial on Webmonkey.

function grade(essay) {



	// Mozilla version



	if (window.XMLHttpRequest) {



		xhr = new XMLHttpRequest();



	}



	// IE version



	else if (window.ActiveXObject) {



		xhr = new ActiveXObject("Microsoft.XMLHTTP");



	}



	essay=encodeURIComponent(essay);



	xhr.open("POST","grade.php");



	xhr.setRequestHeader(



		'Content-Type',



		'application/x-www-form-urlencoded; charset=UTF-8');



	xhr.send(essay);



	xhr.onreadystatechange=function() {



		if (xhr.readyState==4) {



			grade = xhr.responseText;



			alert ("Nice essay. Your grade is " + grade);



		}



	}



	return false;



}