Asynchronous Image load

Difference Image include
<img src="/img/fries.jpg" alt="fries normal load" class="async" />

<img src="/img/transparent.gif" data-src="/img/fries.jpg" alt="fries asynchronous load" class="async" />


$('img.async').each(function() {
 $(this).attr('src', $(this).data('src')).load();
});