为什么我无法在Ajax中使用POST方法获取参数？

Question

Here's what I'm trying using ajax:

var x="";
var xxx= setTimeout(myFunc, 7000);
function myFunc(){
    x=document.forms["form1"]["image"].value;
    if(x!=""){
    var xhttp= new XMLHttpRequest();
    xhttp.onreadystatechange=function(){
    if(xhttp.readyState==4 && xhttp.status==200){
        var z= xhttp.responseText;
        alert(z);
        }
    };
       xhttp.open("POST", "test.php", true);
       xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
       xhttp.send("url="+x);
    }
}

Here's test.php:

<?php
$a= $_POST["url"];
echo $a;
?>

But the alert(z) shows some HTML document, not the URL . What wrong I'm doing? How can I correct it and get parameters from ajax?

Answer 1

Put the following corrections to your js part and test.php file:

• js part:

   ... var params = "url="+ encodeURIComponenet(x); xhttp.open("POST", "test.php", true); xhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); xhttp.setRequestHeader("Content-length", params.length); xhttp.send(params); 

• test.php

   <?php if (isset($_POST["url"]) && !empty($_POST["url"])) { $a = $_POST["url"]; echo $a; } ?>