JavaScript waitForever
Writing mochitests for new features in DevTools can be difficult and time-consuming. There are so many elements interacting in an async manner that I oftentimes find myself using the debugger to debug the debugger! In the case where it's unclear what interaction isn't working properly, I find myself going to a neat utility function: waitForever
. By using this function, paired with await
, I can interact with the page while a given test is running to find the problem!
The JavaScript
waitForever
is a super small snippet:
function waitForever() {
return new Promise(r => {});
}
// Usage:
await waitForever();
The function uses a promise which never resolves, thus no additional statements are triggered while also not locking up the browser. From there I can click around and explore elements to find what I've messed up in my test.
Utility functions like these make web development much easier and more enjoyable. Add this one to your toolbox!

You've probably heard the talk around the water cooler about how promises are the future. All of the cool kids are using them, but you don't see what makes them so special. Can't you just use a callback? What's the big deal? In this article, we'll...

When you say or read "HTML5", you half expect exotic dancers and unicorns to walk into the room to the tune of "I'm Sexy and I Know It." Can you blame us though? We watched the fundamental APIs stagnate for so long that a basic feature...

I've been excited to release this plugin for a long time. MooTools ScrollSpy is a unique but simple MooTools plugin that listens to page scrolling and fires events based on where the user has scrolled to in the page. Now you can fire specific...

I recently received an email from a MooTools developer asking a great question about my LazyLoad class:
"I'm using your LazyLoad MooTools plugin (which is great, by the way). I have been trying to figure out how to modify it so that once an image scrolls into...
Thanks for the tip David! I’ll keep that in mind when working on mochi tests. Have you found any other uses for this snippet?