esbuild-wasm

What is esbuild-wasm?

The esbuild-wasm package is a WebAssembly-based version of the esbuild bundler and minifier. It provides extremely fast build times and is designed to be used in environments where native binaries cannot be executed, such as in browsers or some serverless platforms. It supports transforming, bundling, and minifying JavaScript and TypeScript files.

What are esbuild-wasm's main functionalities?

Bundling JavaScript

This code initializes esbuild-wasm and bundles a JavaScript file, outputting a single bundled file. It demonstrates how to set up and execute a basic bundling process.

const esbuild = require('esbuild-wasm');
esbuild.initialize({ worker: true, wasmURL: '/path/to/esbuild.wasm' }).then(() => {
  esbuild.build({
    entryPoints: ['input.js'],
    bundle: true,
    outfile: 'output.js'
  }).catch(() => process.exit(1));
});

Minifying CSS

This example shows how to use esbuild-wasm to minify a CSS file. It sets up the esbuild environment and performs minification, outputting the minified CSS.

const esbuild = require('esbuild-wasm');
esbuild.initialize({ worker: true, wasmURL: '/path/to/esbuild.wasm' }).then(() => {
  esbuild.build({
    entryPoints: ['input.css'],
    minify: true,
    outfile: 'output.css'
  }).catch(() => process.exit(1));
});

Transpiling TypeScript

This code snippet demonstrates how to transpile TypeScript into JavaScript using esbuild-wasm. It includes setting up the environment, specifying the loader for TypeScript files, and bundling the output.

const esbuild = require('esbuild-wasm');
esbuild.initialize({ worker: true, wasmURL: '/path/to/esbuild.wasm' }).then(() => {
  esbuild.build({
    entryPoints: ['input.ts'],
    loader: { '.ts': 'ts' },
    outfile: 'output.js',
    bundle: true
  }).catch(() => process.exit(1));
});

Other packages similar to esbuild-wasm

webpack

Webpack is a popular JavaScript module bundler with a vast ecosystem of plugins. It offers more configuration options and plugins compared to esbuild-wasm but is generally slower in terms of build speed.

rollup

Rollup is another module bundler that focuses on producing efficient bundles. It is known for its tree-shaking capabilities, which are similar to esbuild-wasm, but Rollup typically has slower build times and less efficient minification.

parcel

Parcel is a web application bundler that requires zero configuration for quick setup. It provides fast build times similar to esbuild-wasm and supports various file types natively, but it might not reach the same speed for larger projects.

README

esbuild

This is the cross-platform WebAssembly binary for esbuild, a JavaScript bundler and minifier. See https://github.com/evanw/esbuild and the JavaScript API documentation for details.

Changelog

0.19.12

• The "preserve" JSX mode now preserves JSX text verbatim (#3605)

  The JSX specification deliberately doesn't specify how JSX text is supposed to be interpreted and there is no canonical way to interpret JSX text. Two most popular interpretations are Babel and TypeScript. Yes they are different (esbuild deliberately follows TypeScript by the way).

  Previously esbuild normalized text to the TypeScript interpretation when the "preserve" JSX mode is active. However, "preserve" should arguably reproduce the original JSX text verbatim so that whatever JSX transform runs after esbuild is free to interpret it however it wants. So with this release, esbuild will now pass JSX text through unmodified:

  // Original code
  let el =
    <a href={'/'} title='&apos;&quot;'> some text
      {foo}
        more text </a>
  
  // Old output (with --loader=jsx --jsx=preserve)
  let el = <a href="/" title={`'"`}>
    {" some text"}
    {foo}
    {"more text "}
  </a>;
  
  // New output (with --loader=jsx --jsx=preserve)
  let el = <a href={"/"} title='&apos;&quot;'> some text
      {foo}
        more text </a>;
  

• Allow JSX elements as JSX attribute values

  JSX has an obscure feature where you can use JSX elements in attribute position without surrounding them with {...}. It looks like this:

  let el = <div data-ab=<><a/><b/></>/>;
  

  I think I originally didn't implement it even though it's part of the JSX specification because it previously didn't work in TypeScript (and potentially also in Babel?). However, support for it was silently added in TypeScript 4.8 without me noticing and Babel has also since fixed their bugs regarding this feature. So I'm adding it to esbuild too now that I know it's widely supported.

  Keep in mind that there is some ongoing discussion about removing this feature from JSX. I agree that the syntax seems out of place (it does away with the elegance of "JSX is basically just XML with {...} escapes" for something arguably harder to read, which doesn't seem like a good trade-off), but it's in the specification and TypeScript and Babel both implement it so I'm going to have esbuild implement it too. However, I reserve the right to remove it from esbuild if it's ever removed from the specification in the future. So use it with caution.

• Fix a bug with TypeScript type parsing (#3574)

  This release fixes a bug with esbuild's TypeScript parser where a conditional type containing a union type that ends with an infer type that ends with a constraint could fail to parse. This was caused by the "don't parse a conditional type" flag not getting passed through the union type parser. Here's an example of valid TypeScript code that previously failed to parse correctly:

  type InferUnion<T> = T extends { a: infer U extends number } | infer U extends number ? U : never
  

2023

All esbuild versions published in the year 2022 (versions 0.16.13 through 0.19.11) can be found in CHANGELOG-2023.md.

2022

All esbuild versions published in the year 2022 (versions 0.14.11 through 0.16.12) can be found in CHANGELOG-2022.md.

2021

All esbuild versions published in the year 2021 (versions 0.8.29 through 0.14.10) can be found in CHANGELOG-2021.md.

2020

All esbuild versions published in the year 2020 (versions 0.3.0 through 0.8.28) can be found in CHANGELOG-2020.md.