CtrlK
BlogDocsLog inGet started
Tessl Logo

tessl/npm-babel--helper-create-class-features-plugin

Babel helper plugin that provides essential functionality for transforming modern JavaScript class features to ES6-compatible code

—

Pending

Quality

Pending

Does it follow best practices?

Impact

Pending

No eval scenarios have been run

SecuritybySnyk

Pending

The risk profile of this skill

Overview
Eval results
Files

Babel Helper Create Class Features Plugin

A Babel helper plugin that provides essential functionality for transforming modern JavaScript class features to ES6-compatible code. It handles compilation of class public and private fields, private methods, and decorators, serving as a foundational component for other Babel plugins that need to transform class-related syntax.

Package Information

  • Package Name: @babel/helper-create-class-features-plugin
  • Package Type: npm
  • Language: TypeScript
  • Installation: npm install @babel/helper-create-class-features-plugin

Core Imports

import { createClassFeaturePlugin, FEATURES } from "@babel/helper-create-class-features-plugin";

For specific utilities:

import { 
  enableFeature, 
  injectInitialization, 
  buildCheckInRHS,
  buildNamedEvaluationVisitor 
} from "@babel/helper-create-class-features-plugin";

Basic Usage

import { createClassFeaturePlugin, FEATURES } from "@babel/helper-create-class-features-plugin";

// Create a plugin for class properties
export default createClassFeaturePlugin({
  name: "transform-class-properties",
  api,
  feature: FEATURES.fields,
  loose: options.loose,
  manipulateOptions(opts, parserOpts) {
    parserOpts.plugins.push("classProperties");
  },
});

// Create a plugin for private methods
export default createClassFeaturePlugin({
  name: "transform-private-methods", 
  api,
  feature: FEATURES.privateMethods | FEATURES.fields,
  loose: options.loose,
});

Architecture

This helper is built around several key components:

  • Plugin Factory: createClassFeaturePlugin function that generates configured Babel plugins
  • Feature System: Bit flag-based feature enablement with consistency checking across plugins
  • Transform Engine: AST transformation logic for class fields, private members, and decorators
  • Private Name Management: Comprehensive system for handling private field and method names
  • Decorator Support: Multiple decorator specification version support (2018-09, 2021-12, 2022-03, 2023-01, 2023-05, 2023-11)

Capabilities

Plugin Creation

Primary factory function for creating Babel plugins that transform class features with configurable options and feature flags.

function createClassFeaturePlugin(options: Options): PluginObject;

interface Options {
  name: string;
  feature: number;
  loose?: boolean;
  inherits?: PluginObject["inherits"];
  manipulateOptions?: PluginObject["manipulateOptions"];
  api?: PluginAPI;
  decoratorVersion?: DecoratorVersionKind | "2018-09";
}

Plugin Creation

Feature Management

Core feature enablement and configuration system that manages the bit flag-based feature system and ensures consistency across multiple class feature plugins.

const FEATURES: {
  readonly fields: number;        // 1 << 1 (2)
  readonly privateMethods: number; // 1 << 2 (4)  
  readonly decorators: number;    // 1 << 3 (8)
  readonly privateIn: number;     // 1 << 4 (16)
  readonly staticBlocks: number;  // 1 << 5 (32)
};

function enableFeature(file: File, feature: number, loose: boolean): void;
function isLoose(file: File, feature: number): boolean;
function shouldTransform(path: NodePath<t.Class>, file: File): boolean;

Feature Management

Field Transformation

Comprehensive private and public field transformation including private name mapping, field initialization, and usage transformation.

function buildPrivateNamesMap(
  className: string,
  privateFieldsAsSymbolsOrProperties: boolean,
  props: PropPath[],
  file: File
): PrivateNamesMap;

function buildFieldsInitNodes(
  ref: t.Identifier | null,
  superClass: t.Expression | null,
  props: PropPath[],
  privateNamesMap: PrivateNamesMap,
  file: File,
  setPublicClassFields: boolean,
  privateFieldsAsSymbolsOrProperties: boolean,
  noUninitializedPrivateFieldAccess: boolean,
  constantSuper: boolean,
  innerBinding: t.Identifier | null
): FieldsInitResult;

Field Transformation

Decorator Support

Multi-version decorator transformation supporting various decorator specifications with proper handling of decorator metadata and class modification.

function hasDecorators(node: t.Class): boolean;
function buildNamedEvaluationVisitor(): Visitor;

type DecoratorVersionKind = 
  | "2023-11" | "2023-05" | "2023-01" 
  | "2022-03" | "2021-12";

Decorator Support

Utilities

Helper utilities for class initialization, computed key extraction, and AST manipulation.

function injectInitialization(
  path: NodePath<t.Class>,
  constructor: NodePath<t.ClassMethod> | undefined,
  instanceNodes: t.ExpressionStatement[],
  referenceVisitor: (visitor: Visitor, state: any) => void,
  lastInstanceNodeReturnsThis: boolean
): void;

function buildCheckInRHS(
  rhs: t.Expression,
  file: File,
  inRHSIsObject?: boolean
): t.Expression;

Utilities

Types

Core Types

type PropNode = 
  | t.ClassProperty 
  | t.ClassPrivateProperty 
  | t.ClassPrivateMethod 
  | t.StaticBlock;

type PropPath = NodePath<PropNode>;

interface PrivateNameMetadata {
  id: t.Identifier;
  static: boolean;
  method: boolean;
  getId?: t.Identifier;
  setId?: t.Identifier;
  methodId?: t.Identifier;
  initAdded?: boolean;
  getterDeclared?: boolean;
  setterDeclared?: boolean;
}

type PrivateNamesMap = Map<string, PrivateNameMetadata>;
Workspace
tessl
Visibility
Public
Created
Last updated
Describes
npmpkg:npm/@babel/helper-create-class-features-plugin@7.28.x
Publish Source
CLI
Badge
tessl/npm-babel--helper-create-class-features-plugin badge