Inside a page I am having a TR on which when user click it change it’s color to blue and arrow color to white. This is achieved by changing elements’ class dynamically.
But due to this what happen is, when user click on TR user saw image loading delay. How to preload that CSS image.
this.className = this.className + " active";
CSS
.table td.arrow div {background-image:url("../stuff/arrow.png");}
tr.active td.arrow div { background-image:
url("../stuff/arrow_active.png"); }

Update
One more thing want to update that static content is getting loaded from other server.
The browser only loads images from the CSS that are shown. So you could place your arrow_active image in a element, that is visible but has no opacity.
But i would suggest you use sprites: Less HTTP requests + no preloading problems: css-tricks.com/css-sprites , alistapart.com/articles/sprites
You could solve your problem like this with pure CSS.
http://jsfiddle.net/Q6dTf/
Alternatively you could use a :before pseudo element if you dont want to add a new HTML element.