Why aren't Web Workers used more? [closed]

Question

Web Workers are a technology that I brush up against from time to time, whether as the subject of blog post, or a mention in a presentation.

During a more recent presentation I attended, the speaker said about web workers:

I'm not really sure why they aren't used more.

I realised, having thought about it, that for a technology with such obvious benefits & use cases, web workers seem to have had a fairly slow, or narrow adoption.

Is there some inherent issue with Web workers that makes them less useful? Am I just looking in the wrong places for examples of their use? Or is it that Javascript programmers in general are not particularly used to creating multi-threaded applications.

Answer 1

Since most answers to this question are a few years old, here's my perspective on the current state of things, as of May 2019.

Web Workers are now supported in commonly-targeted browsers, and I'd argue that browser support is no longer a significant obstacle to their use. Despite that, Web Workers still aren't commonly used, and most web developers I interact with don't use them.

Certainly not every website needs to do enough heavy lifting to justify a Web Worker; many websites don't need JavaScript at all. So, I wouldn't expect to see Web Workers in a majority of websites realistically.

But "heavy lifting" is not the only factor in justifying a Web Worker – another is ease of use. Web Workers are a significant challenge to use in many contexts. Note that the Web Worker API involves splitting your build outputs into separate files, or generating that code (e.g. with Data URIs or fn.toString()) at runtime. Web developers use many different build systems, and often have many dependencies in their projects. Configuring the project to create these additional build artifacts with the right dependencies can be difficult, or at least it varies with the build system you have.

Furthermore, this work almost invariably has to be done by each web developer, for each individual project. You could expect much higher Web Worker adoption if WWs were commonly used inside the popular libraries and frameworks that developers already depend on. But they aren't (for API-related reasons, if I had to guess), even for libraries that do a significant amount of synchronous work. And as long as using the main thread is the default, easiest thing to do, that's what most developers will continue to do.