deloom

English/中文

deloom is a tool for uncompressing and unbundling JavaScript files produced by bundlers and minifiers like webpack, terser, and others. Using Babel AST transformations, it recovers obfuscated or compressed code into a more readable form and disassembles webpack bundles into standalone CommonJS modules.

Features

• Uncompress — Decompress and beautify a single minified JavaScript file: format code, fold constants, remove dead code, expand conditional expressions, and more.
• Unbundle — Extract the module graph from one or more webpack bundle files (e.g., 1.js, 2.js) into independent .cjs files, along with the required webpack runtime helper code.
• Based on Babel parser and traversal, supports modern ECMAScript syntax.
• CLI and programmatic API.

Installation

# Using pnpm (recommended)
pnpm add -D deloom

# Or using npm
npm install --save-dev deloom

Global install:

npm install -g deloom

Quick Start

1. Uncompress a Single File

deloom uncompress input.js output.js

Reads input.js, beautifies it, and writes to output.js. Prettier is used for secondary formatting by default; pass --no-prettier to disable.

Options:

--no-prettier      Disable Prettier formatting
--throw-errors     Throw errors during transformation (default: catch and fallback)
--no-timing        Disable performance timing output

2. Unbundle a Webpack Bundle

deloom unbundle ./dist/chunks ./output

Where ./dist/chunks is a directory containing one or more bundle files (e.g., 1.js, 2.js), and ./output is the output directory. The tool parses all matched files, extracts the module definitions, and generates standalone .cjs files plus a WebpackHelper.cjs helper module.

Options:

--filter <pattern>  File filter pattern, default `*.js`
--no-log            Disable console logging
--no-clean          Do not clean the output directory before running

API Usage

The package exposes two main functions:

formatSource(source, options?)

Beautify a JavaScript string or AST program.

import { formatSource } from 'deloom'

const code = `
var a=1,b=2;console.log(a+b);
`

const result = await formatSource(code, {
  usePrettier: true,
  throwErrors: false,
})

console.log(result)
// =>
// var a = 1;
// var b = 2;
// console.log(3);

unbundle(options)

Unbundle webpack bundle files.

import { unbundle } from 'deloom'

await unbundle({
  entries: ['./dist/chunks/1.js', './dist/chunks/2.js'],
  output: './output',
  log: true,
})

How It Works

uncompress Transformations

A pipeline of Babel visitors is applied in order:

• Normalize string / numeric literal representations
• Constant folding (1 + 2 * 3 → 7)
• Object property shorthand ({a: a} → {a})
• Function expression to arrow function (function(){} → () => {})
• Ternary to if/else (cond ? a() : b() → if/else)
• Logical expression to if (a && b() → if (a) { b() })
• Promise executor parameter renaming ((a, b) → (resolve, reject))
• try-catch parameter renaming (e → caughtError)
• void 0 → undefined
• Sequence expression splitting ((a(), b()) → a(); b())
• Assignment extraction from expressions
• And many more...

unbundle Workflow

1. Parse each bundle file and locate the main module object (a large ObjectExpression where every property is a module function).
2. Traverse each module function, identify require() calls and webpack runtime helpers (require.d, require.r, require.n, etc.).
3. Rewrite module numeric IDs to relative paths (e.g., require(3) → require('./3.cjs')).
4. Replace webpack runtime helper references with calls to WebpackHelper.cjs.
5. Strip the webpack wrapper, keeping only the module body.
6. Analyze dependency graphs.
7. Emit each module as a separate .cjs file with a documentation banner, and generate WebpackHelper.cjs.

Project Structure

├── bin/
│   └── cli.ts               # CLI entry point
├── src/
│   ├── index.ts             # Exports formatSource and unbundle
│   ├── uncompress.ts        # Core uncompression logic (AST transforms)
│   ├── unbundler.ts         # Unbundling core (Extractor class)
│   ├── helper.ts            # Webpack runtime helper code generation
│   └── deps.d.ts            # Type declarations
├── package.json
├── tsconfig.json
├── .prettierrc.json
└── README.md

License

Licensed under the MIT License.

This project is intended for learning and research purposes only. Do not use it to infringe upon the copyrights of others.

Notes

• The unbundled output may contain unresolved references or warnings (Tips); always review the generated files.
• Webpack versions and plugin behaviors vary widely — some patterns may not be fully restored. Issues and pull requests are welcome.