JavaScript的Ajax封装GET和POST

<!DOCTYPE html>
<html>
<head>
    <title>封装ajax</title>
</head>
<body>
<script type="text/javascript">

    function createXHR()
    {
        if(typeof XMLHttpRequest != "undefined")
        {
            return new XMLHttpRequest();
        }
        else if(typeof ActiveXObject != "undefined")
        {
            var versions = [
                "MSXML.2.XMLHttp.6.0",
                "MSXML.2.XMLHttp.3.0",
                "MSXML.2.XMLHttp"
            ];
            for(var i = 0; i<versions.length;i++)
            {
                try{
                    return new ActiveXObject(version[i]);
                }catch(e){
                    // 因类循环会报一个错，跳过些错
                }
            }
        }
        else
        {
            throw new Error("你的系统或浏览器不支持XHR对象！");
        }
    }

    // 名值对转换字符串
    function params(data)
    {
        var arr = [];
        for(var i in data)
        {
            arr.push(encodeURIComponent(i)+"="+encodeURIComponent(data[i]));    
        }
        return arr.join("&");
    }

    // ajax 

    function ajax(obj)
    {
        var xhr=createXHR();
        obj.url=obj.url+"?rand="+Math.random();
        obj.data = params(obj.data);
        if(obj.method === "GET")
        {
            obj.url+=obj.url.indexOf("?") == -1 ?"?"+ obj.data:"&"+obj.data;    
        }

        //  if it's asynchronous
        if(obj.async === true)
        {
            xhr.onreadystatechange = function()
            {
                if(xhr.readyState == 4)
                {                   
                    callback();
                }
            }
        }
        xhr.open(obj.method,obj.url,obj.async);
        if(obj.method === "POST")
        {
            xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
            xhr.send(obj.data);
        }
        else
        {
            xhr.send(null);
        }       

        // iF It's synchronization
        if(obj.async === false)
        {
            callback();
        }

        // 封装重复调用代码
        function callback()
        {
            if(xhr.status === 200)
            {
                obj.success(xhr.responseText);
            }
            else
            {
                alert("错误代码："+xhr.status+"-错误信息："+xhr.statusText);
            }
        }
    }

    //  use ajax

    addEventListener("click",function(){
        ajax({
            method:"POST",
            url:"test.php",
            data:{
                "na&me":"ping",
                "age":18
            },  
            // 将对象传到text，然后对象又回调
            success:function(text)
            {
                console.log("接收success数据为："+text);
            },
            async:false
        });
    },false);
</script>
</body>
</html>
JavaScript的Ajax封装GET和POST

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