ajax(Asynchronous JavaScript and XML)の基本表記

1. Ajax（Asynchronous JavaScript and XML），   JavaScript XML
2. Ajax         XMLHttpRequest。
3.   Ajax           ：
xmlHttpRequest.open("GET", "AjaxServlet", true);

       ：
<script type="text/javascript">
	var xmlHttpRequest = null;
	/* alert(window.ActiveXObject);
	alert(window.XMLHttpRequest); */
	function ajaxSubmit() {

		if (window.ActiveXObject) // IE   
		{
			xmlHttpRequest = new ActiveXObject("Microsoft.XMLHTTP");
		} else if (window.XMLHttpRequest) // IE         
		{
			xmlHttpRequest = new XMLHttpRequest();
		}

		if (null != xmlHttpRequest) {
			


/*
			xmlHttpRequest.open("POST", "AjaxServlet", true);
//       
			xmlHttpRequest.onreadystatechange = ajaxCallback;
//   post    ，         
			[color=darkred]xmlHttpRequest.setRequestHeader("Content-Type","application/x-www-form-urlencoded");[/color]
//        
			xmlHttpRequest.send("v1=" + v1 + "&v2=" + v2);
		
*/

//GET     
var v1=document.getElementsByName("value1")[0].value;
			var v2=document.getElementsByName("value2")[0].value;
			xmlHttpRequest.open("GET", "AjaxServlet?v1="+v1+"&v2="+v2, true);
			
			xmlHttpRequest.onreadystatechange = ajaxCallback;
			xmlHttpRequest.send(null);
}
	}

	function ajaxCallback() {
		//alert("test");
		if (xmlHttpRequest.readyState == 4) {
			if (xmlHttpRequest.status == 200) {
				var Text = xmlHttpRequest.responseText;
				//alert(Text);
				document.getElementById("div1").innerHTML = Text;
			}
		}
	}
</script>