Elm Minification Benchmarks

A tool to help you evaluate what the best minifier for your Elm program is. The metrics are:

• How small is the code after minification?
• How small is the code after minification and brotli compression?
• How fast is the minifier?
• How much disk space does the minifier use, and how many dependencies does it have?
• Does the minifier break the program?

The output table is sorted by brotli size, but feel free to make your own trade-offs and conclusions.

Inspired by the excellent JavaScript minification benchmarks repo.

The winner?

If you use SWC with the settings from the Elm Guide, you seem to get about the smallest size in very little time. It’s not the fastest, but still not even close to a second even on a large Elm app (depending on the computer of course). It has just two dependencies (which are other @swc/ packages). The executable size is roughly comparable to Elm’s executables.

import * as swc from "@swc/core";

const pureFuncs = [ "F2", "F3", "F4", "F5", "F6", "F7", "F8", "F9", "A2", "A3", "A4", "A5", "A6", "A7", "A8", "A9"]; // prettier-ignore

async function minify(code) {
  return (
    await swc.minify(code, {
      compress: {
        pure_funcs: pureFuncs,
        pure_getters: true,
        unsafe_comps: true,
        unsafe: true,
      },
      mangle: {
        reserved: pureFuncs,
      },
    })
  ).code;
}

How to run

1. Clone this repo.
2. Install dependencies: npm install
3. Compile your Elm app: elm make --optimize --output elm.js path/to/your/Main.elm
4. Run this tool on the compiled JS: node bench.js ../path/to/elm.js

How to add a new minifier

1. Install it: npm install --save-exact my-minifier
2. Copy minifiers/(none).js to minifiers/my-minifier.js.
3. Edit the (code) => code function to run your minifier. The function takes a string and returns a string or a promise of a string.
4. Try it with node bench.js example-azimutt.js.

How to add a new configuration for a minifier

1. Copy minifiers/my-minifier.js to minifiers/my-minifier_variation.js.
2. Edit it as you like.
3. Try it with node bench.js example-azimutt.js.

Example

❯ node bench.js example-azimutt.js
┌─────────┬───────────────────────┬──────────┬─────────────┬───────┬───────────────┬─────────┬───────────────┬─────────┬───────────────────────────────────────────────────────┐
│ (index) │ name                  │ version  │ time        │ x     │ size          │ %       │ brotli ⬇      │ %       │ installation size and dependencies                    │
├─────────┼───────────────────────┼──────────┼─────────────┼───────┼───────────────┼─────────┼───────────────┼─────────┼───────────────────────────────────────────────────────┤
│ 0       │ '(none)'              │ ''       │ ''          │ ''    │ '   1.35 MiB' │ ''      │ '    167 KiB' │ ''      │ ''                                                    │
│ 1       │ '@swc/core_elm-guide' │ '1.10.9' │ '   184 ms' │ 'x6'  │ '    411 KiB' │ '-70 %' │ '🏆  101 KiB' │ '-40 %' │ 'https://packagephobia.com/result?p=@swc/core'        │
│ 2       │ 'uglify-js_elm-guide' │ '3.19.3' │ '   2.61 s' │ 'x87' │ '🏆  402 KiB' │ '-71 %' │ '    101 KiB' │ '-39 %' │ 'https://packagephobia.com/result?p=uglify-js'        │
│ 3       │ '@swc/core'           │ '1.10.9' │ '   179 ms' │ 'x6'  │ '    410 KiB' │ '-70 %' │ '    102 KiB' │ '-39 %' │ 'https://packagephobia.com/result?p=@swc/core'        │
│ 4       │ 'terser_elm-guide'    │ '5.37.0' │ '   1.71 s' │ 'x57' │ '    416 KiB' │ '-70 %' │ '    102 KiB' │ '-39 %' │ 'https://packagephobia.com/result?p=terser'           │
│ 5       │ 'uglify-js'           │ '3.19.3' │ '   2.48 s' │ 'x83' │ '    405 KiB' │ '-71 %' │ '    103 KiB' │ '-38 %' │ 'https://packagephobia.com/result?p=uglify-js'        │
│ 6       │ 'uglify-js+esbuild'   │ ''       │ '   1.82 s' │ 'x61' │ '    403 KiB' │ '-71 %' │ '    104 KiB' │ '-38 %' │ ''                                                    │
│ 7       │ 'terser'              │ '5.37.0' │ '   1.38 s' │ 'x46' │ '    419 KiB' │ '-70 %' │ '    104 KiB' │ '-38 %' │ 'https://packagephobia.com/result?p=terser'           │
│ 8       │ 'esbuild_tweaked'     │ '0.24.2' │ '    57 ms' │ 'x2'  │ '    423 KiB' │ '-69 %' │ '    107 KiB' │ '-36 %' │ 'https://packagephobia.com/result?p=esbuild'          │
│ 9       │ 'esbuild'             │ '0.24.2' │ '    51 ms' │ 'x2'  │ '    430 KiB' │ '-69 %' │ '    110 KiB' │ '-34 %' │ 'https://packagephobia.com/result?p=esbuild'          │
│ 10      │ 'bun'                 │ '1.2.0'  │ '🏆  30 ms' │ 'x1'  │ '    432 KiB' │ '-69 %' │ '    110 KiB' │ '-34 %' │ 'https://packagephobia.com/result?p=bun'              │
│ 11      │ '@tdewolff/minify'    │ '2.21.3' │ '    48 ms' │ 'x2'  │ '    434 KiB' │ '-69 %' │ '    114 KiB' │ '-32 %' │ 'https://packagephobia.com/result?p=@tdewolff/minify' │
└─────────┴───────────────────────┴──────────┴─────────────┴───────┴───────────────┴─────────┴───────────────┴─────────┴───────────────────────────────────────────────────────┘