window.function start() {
start();
}


function start() {
window.setInterval(function () {
$( "body" ).css({'background': 'url("images/1.jpg") no-repeat center center fixed', 'background-size': 'cover'});

setTimeout(function(){
$( "body" ).css({'background': 'url("images/2.jpg") no-repeat center center fixed', 'background-size': 'cover'});
}, 2000);
setTimeout(function(){
$( "body" ).css({'background': 'url("images/1.jpg") no-repeat center center fixed', 'background-size': 'cover'});
}, 4000);
}, 3000);

}