ast-kit

2.2.0 verified Sat Apr 25 auth: no javascript

A TypeScript-first toolkit for easy Babel AST generation and manipulation, currently at version 2.2.0 (stable). Provides utilities like babelParse, babelParseFile, walkAST, walkIdentifiers, and AST generation helpers. Released under active development with frequent updates and a v3 beta upgrading to Babel 8. Key differentiators: tree-shakable, full TypeScript support, 100% test coverage, lightweight with only two runtime dependencies. Requires Node.js >=20.19.0 since v2.0.0 (which dropped CJS and older Node versions).

Common errors

error Error [ERR_REQUIRE_ESM]: require() of ES Module /path/to/ast-kit/index.mjs not supported. ↓

cause Package is ESM-only since v2.0.0; calling require() is invalid.

fix

Use import { ... } from 'ast-kit' or dynamic import() instead of require().

error TypeError: babelParse is not a function ↓

cause Using default import (import babelParse from 'ast-kit') instead of named import.

fix

Use import { babelParse } from 'ast-kit'.

error SyntaxError: Unexpected token 'export' ↓

cause Using CommonJS (require) with ESM-only package without transpilation.

fix

Set { type: 'module' } in package.json and use import syntax, or upgrade Node to >=20.19.0.

Warnings

breaking Dropped support for Node.js 16 and 18, and removed CJS build in v2.0.0. ↓

fix Use Node.js >=20.19.0 and switch to ESM imports (import syntax, not require).

deprecated The v3.0.0 beta upgrades Babel to v8, which may introduce breaking changes in AST types and parser options. ↓

fix If using v3 beta, migrate to @babel/types v8 and adjust for new AST node shapes.

gotcha walkIdentifiers may not infer identifiers in function parameters or JSXNamespacedName as references (fixed in v2.1.1). ↓

fix Upgrade to >=2.1.1 to correctly handle these cases.

gotcha The package does not expose a default export; all utilities are named exports. ↓

fix Use named imports like import { babelParse } from 'ast-kit'.

Install

npm install ast-kit

yarn add ast-kit

pnpm add ast-kit

Imports

babelParse

wrong

const { babelParse } = require('ast-kit')

correct

import { babelParse } from 'ast-kit'

Package is ESM-only since v2.0.0; require() will fail.

babelParseFile

wrong

import babelParseFile from 'ast-kit'

correct

import { babelParseFile } from 'ast-kit'

Named export, not default.

walkAST

wrong

import { walk } from 'ast-kit'

correct

import { walkAST } from 'ast-kit'

Function is named walkAST, not walk.

Quickstart

Demonstrates parsing, file reading, AST walking, identifier extraction, and code generation.

import { babelParse, babelParseFile, walkAST, walkIdentifiers, generate } from 'ast-kit'

// Parse a code string
const ast = babelParse('const x = 1 + 2', { sourceType: 'module' })
console.log(ast.program.body[0].type) // 'VariableDeclaration'

// Parse a file
const fileAst = await babelParseFile('./example.js')

// Walk the AST
walkAST(ast, {
  enter(node) {
    console.log('Entering:', node.type)
  },
  leave(node) {
    console.log('Leaving:', node.type)
  }
})

// Walk only identifiers
walkIdentifiers(ast, (id) => {
  console.log('Found identifier:', id.name)
})

// Generate code from AST (requires @babel/generator)
import generateCode from '@babel/generator'
const output = generateCode(ast).code
console.log(output) // 'const x = 1 + 2;'