JavaScript waitForever

By  on  
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!

Recent Features

  • By
    39 Shirts – Leaving Mozilla

    In 2001 I had just graduated from a small town high school and headed off to a small town college. I found myself in the quaint computer lab where the substandard computers featured two browsers: Internet Explorer and Mozilla. It was this lab where I fell...

  • By
    Regular Expressions for the Rest of Us

    Sooner or later you'll run across a regular expression. With their cryptic syntax, confusing documentation and massive learning curve, most developers settle for copying and pasting them from StackOverflow and hoping they work. But what if you could decode regular expressions and harness their power? In...

Incredible Demos

Discussion

  1. Kenji Okamoto

    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?

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!