使用POST方法从javascript向服务器发送json数据的问题

Question

I am trying to see the json data I sent to the server using XMLHttpRequest but it seems that the server is not receiving it, when I run the javascript the alert window will pop up but doesn't print anything. Anyone know how to solve this problem? Thanks

On the client side, Java script

var obj = {"action": "nothing"};

var jsonString = "jsonString=" + JSON.stringify(obj);


var xmlhttp = new XMLHttpRequest();

xmlhttp.open("POST","http://myserver/main.php",true);

xmlhttp.setRequestHeader("Content-type","application/json");
xmlhttp.setRequestHeader("Content-Length",jsonString.length);

xmlhttp.onreadystatechange = function() 
{           
      if(xmlhttp.readyState === 4 && xmlhttp.status === 200){
          alert(xmlhttp.responseText);
      }
}
xmlhttp.send(jsonString);

On the server,php

if(isset($_POST['jsonString'])) 
echo $_POST['jsonString'];

Answer 1

You're sending JSON data, but the content-type is set to application/x-www-form-urlencoded. You should either send form/encoded data (var obj="action=nothing") or set the content-type to JSON (application/json)