Can i use css to java script ....

Question

i will like to style for example the alert box by defining background color ,image ,etc

Answer 1

You can't. You'll have to create your own.
The alert box is a system object, and not subject to CSS. To do this style of thing you would need to create an HTML element and mimic the alert() functionality. The jQuery UI Modal box does a lot of the work for you, http://jqueryui.com/dialog/

https://stackoverflow.com/questions/7853130/how-to-change-the-style-of-alert-box

Answer 2

It's not possible to style alert, prompt and confirm boxes. The style is chosen by the browser.