JavaScript presents several challenges when testing user interface components written using "Atlas." With asynchronous operations like web service calls or animation, you have to start the operation and wait for it to complete without blocking before you can verify the result. Postbacks are just as difficult because you have to perform an action that causes a postback and then have the test resume processing where it left off when the page loads again. We have written a JavaScript testing framework, in the ToolkitTests web project, to eliminate these problems when writing tests for your components.