@ts-bridge/cli/dist/helpers.js

Bridge the gap between ES modules and CommonJS modules with an easy-to-use alternative to `tsc`.

import typescript from 'typescript';
const { factory, SyntaxKind } = typescript;
/**
 * Get the AST for the `importDefault` helper function, i.e.:
 *
 * ```ts
 * function importDefault(module?: any): any {
 *   if (module?.__esModule) {
 *     return module.default;
 *   }
 *
 *   return module;
 * }
 * ```
 *
 * This is based on the `__importDefault` function that TypeScript generates
 * when compiling ES modules to CommonJS. It is used to import the default
 * export from a (CommonJS) module. This checks if the module has a `__esModule`
 * property, and if so, returns `module.default`. Otherwise, it returns the
 * module itself.
 *
 * @param functionName - The name of the function.
 * @returns The AST for the `importDefault` helper function.
 */
export function getImportDefaultHelper(functionName) {
    return factory.createFunctionDeclaration(undefined, undefined, factory.createIdentifier(functionName), undefined, [
        factory.createParameterDeclaration(undefined, undefined, factory.createIdentifier('module'), factory.createToken(SyntaxKind.QuestionToken), factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), undefined),
    ], factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), factory.createBlock([
        factory.createIfStatement(factory.createPropertyAccessChain(factory.createIdentifier('module'), factory.createToken(SyntaxKind.QuestionDotToken), factory.createIdentifier('__esModule')), factory.createBlock([
            factory.createReturnStatement(factory.createPropertyAccessExpression(factory.createIdentifier('module'), factory.createIdentifier('default'))),
        ], true), undefined),
        factory.createReturnStatement(factory.createIdentifier('module')),
    ], true));
}