php - Changing background image src periodically using jQuery and AJAX -

i'm trying have background image of body of page change every (approximatly) n seconds. have php function echoes random image src when call using ajax. replace current body background image src newly generated one, can't work.

here code, there wrong in ?

(function($) {      var $body = $('body');      window.setinterval(function() {         $.ajax({             url: 'http://localhost/some_path/index.php?exec=getnewbkgimgsrc',         }).done(function(data) {             var newimage = new image();             newimage.onload = function() {                 $body.css('background-image', newimage.src);             };             newimage.src = data;         });     }, 5000);  })(window.jquery); 

and php function work :

public function getnewbkgimgsrc() {     echo content_url_dir.'/wallpapers/wallpaper ('.rand(1, 20).').jpg'; } 

could because i'm using localhost ? can mremeber having ajax problems before when developping locally.

edit : clue maybe style property of body element doesn't sseem change / set in firebug. tried $('body').first() , $(document.body) , using url("") (in value of background-image property) doesn't work either. onload event fire however.

thanks help.

why creating new image object if getting url php? set background-image property of body to:

$body.css('background-image', "url('" + data + "')"); 

if using vanilla js:

document.body.style.backgroundimage="url('" + data + "')"; 

see proper format property here: http://www.w3schools.com/cssref/pr_background-image.asp