给初学ajax的人 ajax函数代码

复制代码 代码如下:

/*

调用方式:

1.POST方式

var txt = escape(sender.value); //document.getElementById("<%= txtName.ClientID %>").value);

var data = "name=" + txt + "&pwd=" + txt;

var option = { "url": "handler/Handler.ashx"

, "action": "POST"

, "callback": function(){

if (xmlHttp.readyState == 4) {//服务器给了回应

if (xmlHttp.status == 200) {//服务正确响应

alert(xmlHttp.responseText);

}

xmlHttp = null; //回收资源

}

　　　}

, "data": data

};

ajax(option);

2.GET方式

var txt = escape(sender.value); //document.getElementById("<%= txtName.ClientID %>").value);

var option = { "url": "handler/Handler.ashx&name=" + txt + "&pwd=" + txt

, "action": "POST"

, "callback": function(){

if (xmlHttp.readyState == 4) {//服务器给了回应

if (xmlHttp.status == 200) {//服务正确响应

alert(xmlHttp.responseText);

}

xmlHttp = null; //回收资源

}

　　　}

};

ajax(option);

*/

function ajax(option) {

createXMlHttpRequest(); //创建xmlHttpRequest 对象

if (option != null && option != undefined) {

if (option.url == null && option.url == undefined) {

xmlHttp = null;

alert("缺少必要参数option.url");

return;

}

if (option.action == null && option.action == undefined) {

xmlHttp = null;

alert("缺少必要参数option.action");

return;

}

xmlHttp.open(option.action, option.url, true);

if (option.contentType != null && option.contentType != undefined) {

xmlHttp.setRequestHeader("Content-Type", option.contentType);

} else {

xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

}

if (option.callback != null && option.callback != undefined) {

xmlHttp.onreadystatechange = option.callback;

}

if (option.action.toUpperCase() == "POST") {

xmlHttp.send(option.data);

} else {

xmlHttp.send(null);

}

}

}

var xmlHttp; //调用完成后最好回收下 xmlHttp = null;

/*获取元素*/

function g(arg) {

var t = document.getElementById(arg);

if (null != t && t != undefined) {

return t;

}

t = document.getElementsByName(arg);

if (null != t && t != undefined) {

return t;

}

t = document.getElementsByTagName(arg);

if (null != t && t != undefined) {

return t;

}

}

/*创建ajax请求对象*/

function createXMlHttpRequest() {

try {//Firefox, Chrome, Surfri, Opera+8

xmlHttp = new XMLHttpRequest();

}

catch (ie) {

try {//IE6+

xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");

} catch (ie) {

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

}

}

return xmlHttp;

}