jq数据请求的四种方式

<script>
    $.ajax({
        url:"http://api.caipiao.com/recommend/two-sides",
        type:"POST",
        data:{"code":"bjpks"},
        beforeSend:function(){
            alert("请求前")
        },
        success:function (data) {
           var data=JSON.parse(data);
           console.log(data);
           alert("ajax请求");
        },
        error:function () {
         console.log("请求错误");
        }
    });

    $.get("http://api.caipiao.com/recommend/two-sides",{"code":"bjpks"},function () {
        alert("进入get请求");
    })
    $.post("http://api.caipiao.com/recommend/two-sides",{"code":"bjpks"},function (){
        alert("进入POST请求");
    })


    var xmlhttp=new XMLHttpRequest();
    xmlhttp.open("POST","http://api.caipiao.com/recommend/two-sides",true);
        xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
        xmlhttp.send( "code=bjpks");
        xmlhttp.onreadystatechange=function () {
            if(xmlhttp.readyState==4&&xmlhttp.status==200){
                alert("xmlhttprequest请求");
            }
        }




</script>