https://github.com/pcattori/babel-dead-code-elimination

https://github.com/pcattori/babel-dead-code-elimination

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• Host: GitHub
• URL: https://github.com/pcattori/babel-dead-code-elimination
• Owner: pcattori
• License: mit
• Created: 2024-05-28T20:10:40.000Z (8 months ago)
• Default Branch: main
• Last Pushed: 2024-12-17T02:34:58.000Z (about 1 month ago)
• Last Synced: 2025-01-04T09:44:47.377Z (12 days ago)
• Language: TypeScript
• Size: 111 KB
• Stars: 60
• Watchers: 2
• Forks: 3
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

        
# babel-dead-code-elimination

Composable primitives for dead code elimination in Babel

This package is **not a Babel plugin**, but rather a set of composable primitives to author your own Babel transforms and plugins.

## Install

```sh

npm install babel-dead-code-elimination

```

## deadCodeElimination

Eliminates unused code from the Babel AST by repeatedly removing unreferenced identifiers.

```ts

import { parse } from "@babel/parser"

import generate from "@babel/generator"

import { deadCodeElimination } from "babel-dead-code-elimination"

let source = "..."

let ast = parse(source, { sourceType: "module" })

deadCodeElimination(ast)

let result = generate(ast).code

```

## findReferencedIdentifiers

Find identifiers that are currently referenced in the Babel AST.

Useful for limiting `deadCodeElimination` to only eliminate _newly_ unreferenced identifiers,

as a best effort to preserve any intentional side-effects in the source.

```ts

import { parse } from "@babel/parser"

import generate from "@babel/generator"

import traverse from "@babel/traverse"

import {

  deadCodeElimination,

  findReferencedIdentifiers,

} from "babel-dead-code-elimination"

let source = "..."

let ast = parse(source, { sourceType: "module" })

let referenced = findReferencedIdentifiers(ast)

traverse(ast, {

  /* ... your custom transform goes here ... */

})

deadCodeElimination(ast, referenced)

let result = generate(ast).code

```

## Prior art

Credit to [Jason Miller](https://github.com/developit) for the initial implementation.

Thanks to these projects for exploring dead code elimination:

- [Next.js](https://github.com/vercel/next.js/pull/9652)

- [babel-plugin-eliminator](https://github.com/egoist/babel-plugin-eliminator/blob/d47034ed765352c02d588afdaa40510967332b21/src/index.ts)

- [bling](https://github.com/TanStack/bling/blob/c8ee1d1ae3009ecefc747edaad45a7dfba9ecc9f/packages/bling/src/compilers.ts)