Mocking Ajax requests

HTML

<div onclick="ajax()">click to ajax</div>
<div onclick="reset()">click to reset</div>
<div onclick="show()">value of x</div>

CSS

div{
    cursor:pointer;
}

JavaScript

var x =0;



function show(){
 alert(x)
}

function reset(){
 x =1;
}

function ajax(){
var jsonData = 10
$.ajax({
  type: 'POST',
  dataType: 'json',
  url: '/echo/json/',
  data : { json: JSON.stringify( jsonData ) },
  success: function(data) {
   x = data
  }  
});
    
}