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jsminify

"jsminfy" is a JS minifier written in C. It uses tree-sitter-javascript grammar to create a parser and uses tree-sitter-visitor to visit each node of a JavaScript AST. For each visited node it generates javascript code that is minified.

Installing

npm i @lotuz/jsminify

Usage

jsminify [OPTIONS] [FILE]

FILE must always come last

OPTIONS

  • -h, --help: For printing jsminify help
  • -v, --version: For printing jsminify version
  • -d, --debug: For debugging minification, also helpful for bug report
  • -o, --output: Sets the output file
  • (WIP) -c, --keep-comments: Keeps comments while minifying
  • (WIP) -b, --beautify: For pretty printing file

Building

Initialize git submodules with: git submodules init --recursive --update

Install node-gyp dependencies according to platform and run:

node-gyp configure node-gyp build

Debugging

Debugging relies on gdb

Change require inside index.js to the one with DEBUG in the path

  • node-gyp rebuild --debug
  • gdb node
  • run index.js [OPTIONS] [FILE]

Dependencies (all installed as git submodules under libs/)

please let me know better ways to handle this

Publishing

  • Bump version on jsminify.c and package.json
  • Create git tag
  • Push tag
  • Wait for CI builds
  • run prebuildify-ci download
  • run npm publish

How I tested this (for now)

I used jsminify to minify:

  • angular.js
  • bootstrap.js
  • d3.js
  • ember.prod.js
  • htmlminifier.js
  • jquery-3.4.1.js
  • lodash.js
  • math.js
  • phaser.js
  • react.js
  • particles.js

then I used prettier to beautify the code and diffed the files against the same process done by Uglifyjs.

The diffs shows what other minifications are done by uglifyjs that could be implemented by jsminify, missing minificaiton opportunities and bugs.

Better tests are currently being written in test/

Profiling

I am using gcc.sh to build jsminify and then using perf and flamegraph to create somekind of visualization of what is going on.

I would love to hear about better ways to profile this.

Improvements

Due to how tree-sitter works it might be possible to only re-minify edited parts of a file while developing. Not sure about this, and not sure if this would be valuable to anyone as it is already really fast to minify using jsminify.

Roadmap

  • 1.0.0

    • MINIFICATION
      • Write article about jsminify 1.0.0
      • Write enough tests for common javascript
      • Improve scientific number printing
      • Improve operator spacing
      • Improve decimal digits precision printing: ECMA-256 only requires up to 21 digits. Chrome apparently crops at 16. So: 0.89081309152928522810 becomes 0.8908130915292852
      • Remove comma dangle
      • Check memory allocation/deallocation
      • Check "includes"
      • Test in Windows
      • Test in Mac

  • 1.1.0

    • COMPRESSION
      • Transform scoped parameters identifiers in shorter versions. ex.: function(foo){foo()} => function(a){a()}
      • Remove unnecessary ";" on last statement in a block statement
    • BEAUTIFY (should this be part of jsminify or another minimal library?)
      • Ensure beatiful output