@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

v7.19.0 (2022-09-05)

:eyeglasses: Spec Compliance

• babel-parser
  • #14666 Support private name in decorator member expression (@JLHwung)
• babel-helpers, babel-plugin-proposal-async-generator-functions, babel-preset-env, babel-runtime-corejs2, babel-runtime-corejs3, babel-runtime
  • #14877 Remove one promise tick in yield* (tc39/ecma262#2819) (@nicolo-ribaudo)

:rocket: New Feature

• babel-generator, babel-helpers, babel-parser, babel-plugin-proposal-decorators, babel-plugin-syntax-decorators, babel-runtime-corejs2, babel-runtime-corejs3, babel-runtime
  • #14836 Add 2022-03 decorators version (stage 3) (@nicolo-ribaudo)
• babel-parser
  • #14695 [parser] Make decoratorsBeforeExport default to false (@nicolo-ribaudo)
• babel-generator, babel-parser
  • #14744 Default to hash syntax for Record&Tuple (@nicolo-ribaudo)
• babel-standalone
  • #14867 feat: add proposal-record-and-tuple to standalone (@JLHwung)
• babel-helper-create-regexp-features-plugin, babel-helpers, babel-plugin-proposal-duplicate-named-capturing-groups-regex, babel-plugin-transform-named-capturing-groups-regex, babel-standalone
  • #14805 Add support for the duplicate named capturing groups proposal (@nicolo-ribaudo)

:bug: Bug Fix

• babel-helper-function-name, babel-helper-wrap-function, babel-plugin-transform-classes
  • #14897 Fix: class transform should not drop method definition when key contains non-BMP characters (@JLHwung)
• babel-plugin-transform-typescript
  • #14890 fix: TS plugin shouldn't remove #privateField! (@liuxingbaoyu)
• babel-parser
  • #14819 fix: parse a<b>>>c as a<(b>>>c) (@JLHwung)
• babel-helper-builder-react-jsx
  • #14886 Fix helper-builder-react-jsx compat with Babel 7.9 (@JLHwung)

:nail_care: Polish

• babel-core
  • #11612 Make error message prefixes more descriptive (@eps1lon)
  • #11554 Hide internal @babel/core functions in config errors (@nicolo-ribaudo)

:memo: Documentation

• #14895 docs: remove david-dm from README (@SukkaW)

:house: Internal

• babel-standalone
  • #14863 ship @babel/standalone source maps (@JLHwung)
• babel-core, babel-parser, babel-traverse
  • #14880 Update typescript to 4.8 (@JLHwung)