Registry / babel-walk

babel-walk

library3.0.1jsnpmunverified

Lightweight AST traversal library for Babel ASTs, v3.0.1 (released 2023). Provides simple, ancestor, and recursive walk functions that are significantly faster than babel-traverse (~8-16x). Key differentiators: curried API (since v3) for improved TypeScript inference and caching of visitors; no union syntax support; designed for non-transformational walks where performance matters. Release cadence is irregular, with major breaking changes in v2 (rename from babylon-walk, dropped Node <10) and v3 (curried functions).

npm install babel-walk

github ↗package ↗

INSTALL

IMPORT

SIG · BABEL-WALK

babel-walk

javascriptv3.0.1

Install

—

Import

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Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

simple

✓ import { simple } from 'babel-walk'

✗ const walk = require('babel-walk'); walk.simple(visitors)(node, state); // v3 curried, use walk.simple(visitors)(node, state) not walk.simple(node, visitors, state)

In v3, simple is curried: first call returns a function that takes (node, state). The old (node, visitors, state) signature is gone.

ancestor

✓ import { ancestor } from 'babel-walk'

✗ const ancestor = require('babel-walk/ancestor'); // wrong path; ancestor is a named export from 'babel-walk'

All walkers are named exports from the package root. No subpath exports prior to v3; always import from 'babel-walk'.

recursive

✓ import { recursive } from 'babel-walk'

✗ const recursive = require('babel-walk').recursive; // correct in CJS, but note the curried signature

recursive is also curried in v3: first call returns (node, state) => void. State is mandatory; if omitted, it defaults to the ancestors array in ancestor walker.

Parses Babel AST and uses simple walker with cached visitors; demonstrates curried API and state passing.

import { parse } from '@babel/parser'; import { simple } from 'babel-walk'; const code = 'const x = 1;'; const ast = parse(code, { sourceType: 'module' }); // Create a walker (curried: visitors first, then node+state) const walker = simple({ Identifier(node, state) { console.log(`Found identifier: ${node.name} at line ${node.loc.start.line}`); }, FunctionDeclaration(node, state) { state.functions.push(node.id.name); }, }); const state = { functions: [] }; walker(ast, state); console.log('Functions:', state.functions);

Debug

Known issues

breakingv3.0.0: All functions are now curried. Old call signature walk.simple(node, visitors, state) no longer works.

fix

Change to walk.simple(visitors)(node, state) or destructure import { simple } and call simple(visitors)(node, state).

affects: <=2.0.0

breakingv2.0.0: Package renamed from babylon-walk to babel-walk; old package deprecated.

fix

Replace require('babylon-walk') with require('babel-walk') or import from 'babel-walk'.

affects: <=1.0.0

deprecatedUnion syntax for visitors (e.g., 'NumberLiteral|StringLiteral'(node, state) {}) is not supported.

fix

Use separate visitor functions for each node type or use an alias like Expression.

affects: >=2.0.0

gotchaState argument is required in ancestor walker but defaulted to ancestors array if omitted. In v2, falsy state was replaced by ancestors; in v3, state is always required.

fix

Always pass a state object (can be empty object {}) to ancestor walker to avoid confusing defaults.

affects: >=3.0.0

Errors

Common errors & fixes

TypeError: walk.simple is not a function

Using CommonJS require with default import expecting ESM default export, or using old non-curried API in v3.

fix

Use const { simple } = require('babel-walk'); then simple(visitors)(node, state);

Cannot find module 'babel-walk'

Package not installed or using old package name babylon-walk.

fix

Run npm install babel-walk and ensure import path is 'babel-walk' not 'babylon-walk'.

TypeError: Cannot read properties of undefined (reading 'Function')

Union syntax like 'FunctionDeclaration|VariableDeclaration' used; not supported.

fix

Define separate visitors for each node type, or use a broader alias like Declaration.

Upgrade

Version history

3.0.1latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

6 hits · last 30 days

node

Resources

githubhttps://github.com/pugjs/babel-walk ↗

packagehttps://www.npmjs.com/package/babel-walk ↗