ts-jest VS esbuild

Argument of type X is not assignable to parameter of type 'never' #2610

First, you can't use jest right out of the box, becuase Jest does not support ECMA script nor Typescript. For that, you need to use another dependency like ts-jest, which is a wrapper of jest itself. And maybe even a Babel preset if I need it to work with Babel.. Let's see what we have to do to get this to work.

use ts-jest and set up Paths Re-Map

Jest's out of the box config for TS doesn't do any type checking. You can integrate https://kulshekhar.github.io/ts-jest/ or you can call ‘tsc’ yourself separately

ts-jest has had some strange performance issues and workarounds in the past, though I haven’t used it very recently so it might have fixed those by now.

Since we're working with TypeScript, we can use ts-jest, which conveniently brings Jest along for the ride:

I want to save you from manually copying the snippets one by one, so here is a Gist with the complete test file. This can be easily executed with Jest (or ts-jest for TypeScript).

See the Jest configuration docs to learn more about Jest configuration. ts-jest also has good documentation.

Using @swc/jest to compile code to CommonJS is much faster than babel-jest, ts-jest which have long cold starts when executing tests in a large project.

Why esbuild? compared to other tools esbuild keeps things minimal, it is very fast(the fastest bundler as of today) and supports typescript and esm by default.

Instant Hot Module Replacement (HMR): During development, Vite only processes the changed files and updates them in the browser instantly, making it incredibly fast and responsive. Optimized Build Process: Vite uses esbuild under the hood for fast JavaScript transpilation, which is significantly faster than Babel. Production Build with Rollup: For production builds, Vite uses Rollup, a highly efficient bundler that produces optimized code.

We have transitioned to using Esbuild for our project's build process and, experiencing a substantial increase in speed compared to our previous setup with Webpack. The primary bottleneck we faced with Webpack was its long build times. Now, with Esbuild integrated into our development environment, our build times have been dramatically reduced to about five seconds, significantly enhancing the efficiency of our workflow.

However, new tools such as SWC and esbulid now also support JS code compression, and their execution efficiency is higher. After all, Rust or Go inherently have much higher execution efficiency than JS.

When executing esbuild bundled code with --platform=node you may have come across one of the following runtime errors:

npm packages dramatically sped up the productivity of developers by being able to leverage other developers' work. However, it had a major disadvantage: cjs was not compatible with web browsers. To solve this problem, the concept of bundlers was born. browserify was the first bundler which essentially worked by traversing an entry point and "bundling" all the require()-ed code into a single .js file compatible with web browsers. As time went on, other bundlers with additional features and differentiators were introduced. Most notably webpack, parcel, rollup, esbuild and vite (in chronological order).

Using a more raw toolchain is also a good way to speed things up; the SWC website shows it to be 20 to 70 times faster than Babel, and there are tons of speed advantages in complex real-world applications, which proves that rawness can be a big help in speeding things up. Instead of vite-plugin-react, you can use @vitejs/plugin-react-swc, with LightningCSS instead of PostCSS, SWC or esbuild instead of Babel, etc. etc. to achieve better performance.

Babel with 49,577,061 npm downloads per week, is the most used tool for JavaScript transformation, we looked at Esbuild as a replacement but many functionalities, most notably loadable support, are missing. Another alternative SWC, written in Rust, supports all the necessary functionalities we need, and on top of that it has APIs similar to Babel, making migration much smoother than other alternatives:

Added a plugin to exclude vendor sourcemaps from the scripts (big reduction) exclude node_modules from source map Issue #1685 · evanw/esbuild · GitHub