给初学ajax的人,

这是原生的ajax,稍稍的封装了下,

对了,option为json格式的数据,对此可先看这个

 

 

/*
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;
}