1var datastring = $("#contactForm").serialize();
2$.ajax({
3    type: "POST",
4    url: "your url.php",
5    data: datastring,
6    dataType: "json",
7    success: function(data) {
8        //var obj = jQuery.parseJSON(data); if the dataType is not specified as json uncomment this
9        // do what ever you want with the server response
10    },
11    error: function() {
12        alert('error handling here');
13    }
14});

1$(function(){
2  $('form').on('submit', function(e){
3    e.preventDefault();
4    $(this).serializeObject().done(function(o){
5      if(window.console) console.log(o);
6      var j = JSON.stringify(o);
7      alert(j);
8      //window.open("data:image/png;base64," + o.userfile.data);
9    });
10  });
11});

1$.fn.serializeObject = function()
2{
3   var o = {};
4   var a = this.serializeArray();
5   $.each(a, function() {
6       if (o[this.name]) {
7           if (!o[this.name].push) {
8               o[this.name] = [o[this.name]];
9           }
10           o[this.name].push(this.value || '');
11       } else {
12           o[this.name] = this.value || '';
13       }
14   });
15   return o;
16};