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
    Page Visibility API

    One event that's always been lacking within the document is a signal for when the user is looking at a given tab, or another tab. When does the user switch off our site to look at something else? When do they come back?

  • 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
    dwImageProtector Plugin for jQuery

    I've always been curious about the jQuery JavaScript library. jQuery has captured the hearts of web designers and developers everywhere and I've always wondered why. I've been told it's easy, which is probably why designers were so quick to adopt it NOT that designers...

  • By
    Image Manipulation with PHP and the GD Library

    Yeah, I'm a Photoshop wizard. I rock the selection tool. I crop like a farmer. I dominate the bucket tool. Hell, I even went as far as wielding the wizard wand selection tool once. ...OK I'm rubbish when it comes to Photoshop.

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!