lz-mini-js

Compress source js code to no-dependencies self-decompressable js code.
lz-mini-js aims to provide as small output js code as possible and don't rely on external libraries for self-decompress.

Usage

CLI

npx lz-mini-js file.js file.lz.js

This command creates compressed js from file.js and write content to file.lz.js.
The result is fully standalone and does not require any dependencies to decompress itself. So it can be used as is in browsers or nodejs if you want.

API

Module is pretty simple:

const lzJs = require('lz-mini-js');
// ...
const compressedMinifiedCode = await lzJs('function decompressed() { return 42; }');
// write compressedMinifiedCode to file or pass anywhere else

lz-mini-js will minify only self-decompressor code using uglifyjs, source code to be compressed never minified by lz-mini-js.

If you want minify self-decompressor code by youself, pass false to second parameter:

const compressedCode = await lzJs(..., false);
// false means do not minify self-decompressor code
// here we can pass compressedCode to preferred minifier

How it works?

It uses lz-string lib for compressing and decompressing code, but with some tricks to reduce space usage in js code context. For compressing used lz-string itself, for decompressing - inlined version of decompressor.

Because of inlined decompressor lz-mini-js is not situable for very small scripts (~1k bytes and less), in this case decompressor itself is too big and compression profit is not notable. That's because we need to minify it by maximum.

To make self-decompressor extremely lightweight (~344 bytes using uglifyjs) it was almost fully rewritten with many assumptions. The main is compressed code string is always correct and we don't need to make any checks.

You can see inlined decompressor code in file src/lz-decompress.js, it's rewriten version of lz-string function _decompress.