//1 创建对象
var xmlHttp;
function createXMLHttpRequest(){
if(window.ActiveXObject)
xmlHttp = new ActiveXObject("Microsoft.XMLHttp");
else if(widow.XMLHttpRequest)
xmlHttp = new XMLHttprequest();
}
//2建立请求
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var firstName = document.getElementById("firstName").value;
var url= "9-3.aspx?"+ new Date().getTime();
xmlHttp.open("GET",url+ "firstName=" + firstName ,ture)//ture表示异步 get方法在提交数据时候在queryString 中发送数据
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xmlHttp.open("POST",url);//第4步发送数据时候用xmlHttp.send(firstName)
//3异步对象链接服务器
xmlHttp.onreadystatechange = function(){
if(xmlHttp.readyState == 4 && xmlHttp.status == 200)
var responseDiv = document.getElementById("serverResponse");//xmlHttp.responseText服务器的返回并赋值
responseDiv.innerHTML = decodeURI(xmlHttp.responseText); //解码
}
//4数据发送
xmlHttp.send(null)
2步骤当为post时候
xmlHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");