babel-plugin-annotate-react-code.ts — react Source File

Source Code

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

import type * as BabelCore from '@babel/core';
import {NodePath} from '@babel/core';
import * as t from '@babel/types';

export default function AnnotateReactCodeBabelPlugin(
  _babel: typeof BabelCore,
): BabelCore.PluginObj {
  return {
    name: 'annotate-react-code',
    visitor: {
      Program(prog): void {
        annotate(prog);
      },
    },
  };
}

function annotate(program: NodePath<t.Program>): void {
  function traverseFn(fn: BabelFn): void {
    if (!shouldVisit(fn)) {
      return;
    }

    fn.skip();

    const body = fn.node.body;
    if (t.isBlockStatement(body)) {
      body.body.unshift(buildTypeOfReactForget());
    }
  }

  program.traverse({
    FunctionDeclaration: traverseFn,
    FunctionExpression: traverseFn,
    ArrowFunctionExpression: traverseFn,
  });
}

function shouldVisit(fn: BabelFn): boolean {
  return (
    // Component declarations are known components
    (fn.isFunctionDeclaration() && isComponentDeclaration(fn.node)) ||
    // Otherwise check if this is a component or hook-like function
    isComponentOrHookLike(fn)
  );
}

function buildTypeOfReactForget(): t.Statement {
  // typeof globalThis[Symbol.for("react_forget")]
  return t.expressionStatement(
    t.unaryExpression(
      'typeof',
      t.memberExpression(
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