javascript 使用AJAX技术

1、创建XmlHttprequest对象

    <script language="javascript" type="text/javascript">
        var xmlHttp;
        if (window.ActiveXObject)
            xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
        else if (window.XMLHttpRequest)
            xmlHttp = new XMLHttpRequest();
    </script>

2、ajaxgold框架函数，使用ajaxgold提供的四个函数可以轻松实现各类请求

function getDataReturnText(url, callback){
	var XMLHttpRequestObject = false;
	if (window.XMLHttpRequest)
		XMLHttpRequestObject = new XMLHttpRequest();
	else if (window.ActiveXObject)
		XMLHttpRequestObject = new ActiveXObject("Microsoft.XMLHTTP");
	
	if(XMLHttpRequestObject) {
		XMLHttpRequestObject.open("GET", url);
		
		XMLHttpRequestObject.onreadystatechange = function(){
			if(XMLHttpRequestObject.readyState == 4 && XMLHttpRequestObject.status == 200){
				callback(XMLHttpRequestObject.responseText);
				delete XMLHttpRequestObject;
				XMLHttpRequestObject = null;
			}
		}
		XMLHttpRequestObject.send(null);
	}
}

function getDataReturnXML(url, callback){
	var XMLHttpRequestObject = false;
	if (window.XMLHttpRequest)
		XMLHttpRequestObject = new XMLHttpRequest();
	else if (window.ActiveXObject)
		XMLHttpRequestObject = new ActiveXObject("Microsoft.XMLHTTP");
	
	if(XMLHttpRequestObject) {
		XMLHttpRequestObject.open("GET", url);
		
		XMLHttpRequestObject.onreadystatechange = function(){
			if(XMLHttpRequestObject.readyState == 4 && XMLHttpRequestObject.status == 200){
				callback(XMLHttpRequestObject.responseXML);
				delete XMLHttpRequestObject;
				XMLHttpRequestObject = null;
			}
		}
		XMLHttpRequestObject.send(null);
	}
}

function postDataReturnText(url, data, callback){
	var XMLHttpRequestObject = false;
	if (window.XMLHttpRequest)
		XMLHttpRequestObject = new XMLHttpRequest();
	else if (window.ActiveXObject)
		XMLHttpRequestObject = new ActiveXObject("Microsoft.XMLHTTP");
	
	if(XMLHttpRequestObject) {
		XMLHttpRequestObject.open("POST", url);
		XMLHttpRequestObject.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
		
		XMLHttpRequestObject.onreadystatechange = function(){
			if(XMLHttpRequestObject.readyState == 4 && XMLHttpRequestObject.status == 200){
				callback(XMLHttpRequestObject.responseText);
				delete XMLHttpRequestObject;
				XMLHttpRequestObject = null;
			}
		}
		XMLHttpRequestObject.send(data);
	}
}

function postDataReturnXML(url, data, callback){
	var XMLHttpRequestObject = false;
	if (window.XMLHttpRequest)
		XMLHttpRequestObject = new XMLHttpRequest();
	else if (window.ActiveXObject)
		XMLHttpRequestObject = new ActiveXObject("Microsoft.XMLHTTP");
	
	if(XMLHttpRequestObject) {
		XMLHttpRequestObject.open("POST", url);
		XMLHttpRequestObject.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
		
		XMLHttpRequestObject.onreadystatechange = function(){
			if(XMLHttpRequestObject.readyState == 4 && XMLHttpRequestObject.status == 200){
				callback(XMLHttpRequestObject.responseXML);
				delete XMLHttpRequestObject;
				XMLHttpRequestObject = null;
			}
		}
		XMLHttpRequestObject.send(data);
	}
}