rs-module-lexer

ES module parser powered by Rust.

This package is a Rust version of es-module-lexer

Motivation

es-module-lexer cannot parse jsx / ts / tsx files, we need transform ts to js using esbuild / swc first, and then parse :

import { parse } from 'es-module-lexer'
import { transformSync } from 'esbuild'

// 1. transform ts to js
const js = transformSync(ts)
// 2. parse modules
const result = parse(js)

rs-module-lexer resolved this problem, it can parse the ts(x) file directly.

Install

  pnpm i -D rs-module-lexer

Usage

import { parseAsync } from 'rs-module-lexer'
// Sync: import { parse } from 'rs-module-lexer'

const { output } = await parseAsync({
  input: [
    {
      filename: 'index.ts',
      code: `
        export const member = 5
        import { useState } from 'react'
      `,
    },
    // ... other files
  ],
})

// [ { n: 'react', s: 67, e: 72, ss: 41, se: 73, d: -1, a: -1, t: 1 } ]
console.log(output[0].imports)
// [ { n: 'member', ln: 'member', s: 22, e: 28, ls: 22, le: 28 } ]
console.log(output[0].exports)

For details of the parse results, please see es-module-lexer.

Migration from `es-module-lexer`

- import { init, parse } from 'es-module-lexer'
- await init
- const [imports, exports, facade, hasModuleSyntax] = parse(code)

+ import { parseAsync } from 'rs-module-lexer'
+ const { output } = await parseAsync({ input: [{ filename: 'index.ts', code }] })
+ const { imports, exports, facade, hasModuleSyntax } = output[0]

rs-module-lexer can parse multiple files at once, the syntax is auto detect based on filename.

Benchmark

[TS]
es-module-lexer average: 171.6ms 
rs-module-lexer average: 24.7ms 🎉
[JS]
es-module-lexer average: 32.6ms 
rs-module-lexer average: 23.9ms 🎉

License

MIT