@babel/types

What is @babel/types?

The @babel/types package is a part of the Babel compiler ecosystem. It contains methods for building and validating AST (Abstract Syntax Tree) nodes for JavaScript-like languages. It is commonly used for creating and transforming code within Babel plugins.

What are @babel/types's main functionalities?

AST Node Creation

This feature allows the creation of AST nodes. The code sample demonstrates how to create an identifier and a numeric literal using the package.

const t = require('@babel/types');
const identifier = t.identifier('myVariable');
const numericLiteral = t.numericLiteral(123);

AST Node Validation

This feature is used to validate if a node is of a specific type. The code sample checks if a node is an identifier.

const t = require('@babel/types');
const isValid = t.isIdentifier(t.identifier('myVariable'));

AST Node Transformation

This feature allows the transformation of AST nodes. The code sample creates a binary expression node that represents 'a + b'.

const t = require('@babel/types');
const binaryExpression = t.binaryExpression('+', t.identifier('a'), t.identifier('b'));

AST Node Traversal

This feature is not directly provided by @babel/types but is often used in conjunction with it. It involves traversing the AST and updating nodes. The code sample renames an identifier within the AST.

const t = require('@babel/types');
const traverse = require('@babel/traverse').default;
const ast = t.file(t.program([t.expressionStatement(t.identifier('myVariable'))]));
traverse(ast, {
  enter(path) {
    if (t.isIdentifier(path.node)) {
      path.node.name = 'newVariable';
    }
  }
});

Other packages similar to @babel/types

acorn

Acorn is a small, fast, JavaScript-based JavaScript parser. It produces an abstract syntax tree similar to the one produced by @babel/types but does not include the same utilities for building or validating nodes.

esprima

Esprima is another JavaScript parser that produces an AST. It is used for static analysis and other code transformation tasks, similar to @babel/types, but it has its own API and does not provide the same helper functions for node creation and validation.

recast

Recast is a JavaScript AST manipulation library that uses Esprima under the hood. It provides a different set of utilities for parsing, transforming, and printing code, and it preserves source formatting, which is different from @babel/types.

README

@babel/types

Babel Types is a Lodash-esque utility library for AST nodes

See our website @babel/types for more information or the issues associated with this package.

Install

Using npm:

npm install --save-dev @babel/types

or using yarn:

yarn add @babel/types --dev

Changelog

v7.15.0 (2021-08-04)

:eyeglasses: Spec Compliance

• babel-parser
  • #13523 feat(ts): raise error for abstract property with initializer (@fedeci)

:rocket: New Feature

• babel-parser
  • #13229 Add attachComment parser option to disable comment attachment (@JLHwung)
• babel-standalone
  • #13476 standalone: update preset-stage-* (@sosukesuzuki)
  • #13555 feat: support hack pipeline in @babel/standalone (@JLHwung)
• babel-parser, babel-preset-env
  • #13387 Enable top-level await parsing by default (@nicolo-ribaudo)
• babel-plugin-transform-typescript, babel-preset-typescript
  • #13324 Support TypeScript const enums (@nicolo-ribaudo)
• babel-plugin-transform-typescript
  • #13528 feat(typescript): implement namespace alias (@colinaaa)
• babel-core, babel-helper-create-class-features-plugin, babel-helper-module-transforms, babel-plugin-transform-modules-commonjs
  • #13290 feat: add noIncompleteNsImportDetection assumption to plugin-transform-modules-commonjs (@fedeci)
• babel-plugin-transform-react-display-name
  • #13501 Add display name after create context (@JLHwung)
• babel-parser, babel-plugin-proposal-pipeline-operator, babel-plugin-syntax-pipeline-operator
  • #13416 Hack-pipe proposal with % topic token (@js-choi)
• babel-generator, babel-parser, babel-plugin-proposal-pipeline-operator, babel-plugin-syntax-pipeline-operator, babel-traverse, babel-types
  • #13191 Add support for the "Hack" pipeline proposal (@js-choi)
• babel-plugin-transform-runtime
  • #13398 Expose @babel/eslint-parser/experimental-worker (@nicolo-ribaudo)
• babel-compat-data, babel-helper-compilation-targets, babel-preset-env
  • #13448 Add support for rhino as a compilation target (@gausie)
• babel-compat-data, babel-parser, babel-preset-env
  • #13554 Enable ergonomic brand checks (#priv in) by default (@nicolo-ribaudo)

:bug: Bug Fix

• babel-parser, babel-plugin-transform-typescript
  • #13513 [ts] support optional chain call with generic (@lala7573)
• babel-plugin-transform-typescript
  • #13605 Handle typescript function overloading in a default export (@tony-go)
• babel-parser
  • #13536 Fix %== parsing in hack pipes (@nicolo-ribaudo)
  • #13426 parser: Fix Hack/smart-pipe error positions (@js-choi)
  • #13622 fix(ts): raise error for export default interface {} (@a-tarasyuk)

:memo: Documentation

• #13607 chore(doc): add jest specific pckg command (@tony-go)

---

• See CHANGELOG - v7.0.0 to v7.14.9 for v7.0.0 to v7.14.9 changes.
• See CHANGELOG - v7 prereleases for v7.0.0-alpha.1 to v7.0.0-rc.4 changes.

We have to split the v7 changelog in multiple files otherwise it's too big to render on GitHub.