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

Incredible Demos

  • By
    Highlighter: A MooTools Search & Highlight Plugin

    Searching within the page is a major browser functionality, but what if we could code a search box in JavaScript that would do the same thing? I set out to do that using MooTools and ended up with a pretty decent solution. The MooTools JavaScript Class The...

  • By
    MooTools Accordion: Mouseover Style

    Everyone loves the MooTools Accordion plugin but I get a lot of requests from readers asking me how to make each accordion item open when the user hovers over the item instead of making the user click. You have two options: hack the original plugin...

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!