How to know that a time consuming CSS operation (rendering) has completed

Is there a way to know when a time consuming CSS oper开发者_Go百科ation (setting webkit columns of a large page on a mobile device) has completed?

You can do the following:

1. Set callback with setTimeout with the minimal time, 1 millisecond for example.
2. Do your CSS operations.
3. Your callback will be invoked as fast as CSS operations will be completed and browser will be ready for new actions.