JavaScript waitForTime

By  on  

I write a lot of tests for new features within Firefox DevTools. We have hundreds of "mochitests" which open the browser and perform synthetic actions like clicking, typing, and other user actions. I've previously written about waitForever which essentially halts following actions without locking the browser. Another utility I enjoy is waitForTime, an async JavaScript function that I can await to give breathing time between two tasks.

Whenever I want to wait a given amount of time between tasks, I employ this function:

function waitForTime(ms) {
  return new Promise(r => setTimeout(r, ms));
}

/* Usage */
await waitForTime(200);
// ...do other thing...
await waitForTime(200);
// ...do next thing ...

It's important to point out that most waitForTime calls don't appear in the final test, since arbitrary timeouts lead to intermittent test failures, but they are helpful in knowing where I need to add polling for some other condition!

Recent Features

  • By
    CSS vs. JS Animation: Which is Faster?

    How is it possible that JavaScript-based animation has secretly always been as fast — or faster — than CSS transitions? And, how is it possible that Adobe and Google consistently release media-rich mobile sites that rival the performance of native apps? This article serves as a point-by-point...

  • By
    CSS Filters

    CSS filter support recently landed within WebKit nightlies. CSS filters provide a method for modifying the rendering of a basic DOM element, image, or video. CSS filters allow for blurring, warping, and modifying the color intensity of elements. Let's have...

Incredible Demos

  • By
    MooTools, mediaboxAdvanced, and Mexico

    The lightbox is probably one of my favorite parts of the Web 2.0 revolution. No more having to open new windows (which can bog down your computer quite a bit) to see a larger image, video, etc. Instead, the item loads right into the...

  • By
    PHP IMDB Scraper

    It's been quite a while since I've written a PHP grabber and the itch finally got to me. This time the victim is the International Movie Database, otherwise known as IMDB. IMDB has info on every movie ever made (or so it seems). Their...

Discussion

  1. Pavan

    I have this kind of a function in all my apps and I usually name is delay.

  2. Dubbya

    You don’t have to put “async” in front of the function?

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