Immediately Executing setInterval with JavaScript

By  on  

Employing setInterval for condition polling has really been useful over the years. Whether polling on the client or server sides, being reactive to specific conditions helps to improve user experience. One task I recently needed to complete required that my setInterval immediately execute and then continue executing.

The conventional and best way to immediately call a function at the beginning of a setInterval is to actually call the function before the initial setInterval` is called:

myFunction();
setInterval(myFunction, 1000); // Every second

If you truly want to isolate the function call to the setInterval, you can use this trick of self-executing function that returns itself:

// Use a named function ...
setInterval(function myFunction() {
  // Do some stuff
  // ...

  // ... then return this function
  return myFunction;

// () self-executes the function
}(), 3000)

The down side to this pattern is that it causes a maintenance issue, where the next developer doesn't understand what is going on.

Maintenance is an important part of being a good engineer, so at the very least, documentation in the form of comments or a helper function should be required. If you really want to have a self-executing setInterval, you've got it!

Recent Features

  • By
    CSS Animations Between Media Queries

    CSS animations are right up there with sliced bread. CSS animations are efficient because they can be hardware accelerated, they require no JavaScript overhead, and they are composed of very little CSS code. Quite often we add CSS transforms to elements via CSS during...

  • By
    CSS @supports

    Feature detection via JavaScript is a client side best practice and for all the right reasons, but unfortunately that same functionality hasn't been available within CSS.  What we end up doing is repeating the same properties multiple times with each browser prefix.  Yuck.  Another thing we...

Incredible Demos

Discussion

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