Detect Generator Functions with JavaScript

By  on  

In the current JavaScript climate of new syntaxes, features, and using loads of external libraries, it seems harder than ever to be sure what your functions are being given or even what the data represents. Of course, we've come up with Flow and TypeScript to help, but we can't count on those always being available. That's why I like doing my own detection with JavaScript, especially when it comes to function types.

To detect if a function is a generator or async generator function, you can use the following code:

// Sample generator function
function* sampleGenerator() {}
sampleGenerator.constructor.name
// "GeneratorFunction"

async function* sampleGenerator() {}
sampleGenerator.constructor.name
// "AsyncGeneratorFunction"

Coincidentally, you can also detect a regular async function with:

async function asyncThing() {}
asyncThing.constructor.name
// "AsyncFunction"

It's always important to know if the code you're using is sync, async, or a generator, but if you're using external libraries or want to write comprehensive tests, these types of detections may be necessary.

Recent Features

  • By
    How I Stopped WordPress Comment Spam

    I love almost every part of being a tech blogger:  learning, preaching, bantering, researching.  The one part about blogging that I absolutely loathe:  dealing with SPAM comments.  For the past two years, my blog has registered 8,000+ SPAM comments per day.  PER DAY.  Bloating my database...

  • By
    Welcome to My New Office

    My first professional web development was at a small print shop where I sat in a windowless cubical all day. I suffered that boxed in environment for almost five years before I was able to find a remote job where I worked from home. The first...

Incredible Demos

Discussion

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