es-module-lexer 2.3.1: init, parse

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify pkg:npm/es-module-lexer@2.3.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/es-module-lexer@2.3.1
Demonstrate these symbols/APIs:
  - init
  - parse

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:d39915e28d535210c66dcf8432bb9f78d9bc7d40ecfb839362c5fb76b3bd4829","contract":["init resolves when the WebAssembly lexer is initialized","parse extracts static imports, dynamic imports, and import attributes","parse extracts named and default exports with export names and local names","parse identifies facade re-export modules and distinguishes ESM from plain scripts"],"goal":"verify pkg:npm/es-module-lexer@2.3.1","kind":"HOW","packages":["pkg:npm/es-module-lexer@2.3.1"],"schemaVersion":1,"symbols":["init","parse"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/es-module-lexer@2.3.1"],"schemaVersion":1,"subject":"pkg:npm/es-module-lexer@2.3.1","symbols":["init","parse"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-es-module-lexer",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-es-module-lexer",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "es-module-lexer": "2.3.1"
      }
    },
    "node_modules/es-module-lexer": {
      "version": "2.3.1",
      "resolved": "https://registry.npmjs.org/es-module-lexer/-/es-module-lexer-2.3.1.tgz",
      "integrity": "sha512-shc1dbU90Yl/xq1QrC7QRtfcwURZuVRfPhZbDoldJ1cn1gzDvBaBWlv0eFolj5+0znnPJz5TXLxsN77X/12KTA==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-es-module-lexer",
  "version": "1.0.0",
  "private": true,
  "description": "verify pkg:npm/es-module-lexer@2.3.1",
  "main": "src/index.js",
  "license": "MIT-0",
  "dependencies": {
    "es-module-lexer": "2.3.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/es-module-lexer@2.3.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/es-module-lexer@2.3.1"
  ],
  "symbols": [
    "init",
    "parse"
  ]
}

const { init, parse } = require('es-module-lexer');

/**
 * Initializes the lexer and parses ES module source code.
 * @param {string} source - JavaScript/ESM source code to parse.
 * @param {string} [name] - Optional filename for error reporting.
 * @returns {Promise<[readonly any[], readonly any[], boolean, boolean]>}
 */
async function parseModule(source, name) {
  await init;
  return parse(source, name);
}

module.exports = {
  init,
  parse,
  parseModule
};

import assert from 'node:assert/strict';
import { createRequire } from 'node:module';

const require = createRequire(import.meta.url);
const { init, parse, parseModule } = require('../src/index.js');
const esModuleLexer = require('es-module-lexer');

// 1. init resolves when the WebAssembly lexer is initialized
assert.strictEqual(typeof init.then, 'function', 'init must be a Promise');
assert.strictEqual(typeof parse, 'function', 'parse must be a function');
assert.strictEqual(parse, esModuleLexer.parse, 'parse must match es-module-lexer.parse');
await init;

// 2. parse extracts static imports, dynamic imports, and import attributes
const codeWithImports = `
  import defaultItem, { itemA, itemB as renamedB } from 'pkg-dep';
  import data from './data.json' with { type: 'json' };
  const lazy = import('./lazy-module.js');
  const metaUrl = import.meta.url;
`;
const [imports, exports, facade, hasModuleSyntax] = await parseModule(codeWithImports);

assert.strictEqual(imports.length, 4, 'must detect 4 import expressions');
// static import
assert.strictEqual(imports[0].n, 'pkg-dep');
assert.strictEqual(imports[0].d, -1, 'static import d=-1');
assert.strictEqual(codeWithImports.slice(imports[0].s, imports[0].e), 'pkg-dep');

// import with attributes
assert.strictEqual(imports[1].n, './data.json');
assert.strictEqual(imports[1].d, -1);
assert.ok(imports[1].at !== null, 'import attributes must be parsed');
assert.deepStrictEqual(imports[1].at, [['type', 'json']]);

// dynamic import
assert.strictEqual(imports[2].n, './lazy-module.js');
assert.ok(imports[2].d >= 0, 'dynamic import d>=0');

// import.meta
assert.strictEqual(imports[3].d, -2, 'import.meta d=-2');
assert.strictEqual(hasModuleSyntax, true);

// 3. parse extracts named and default exports with export names and local names
const codeWithExports = `
  export const value = 42;
  export function helper() {}
  const localVal = 100;
  export { localVal as publicAlias };
  export default class MainClass {}
`;
const [importsExp, exportsExp] = await parseModule(codeWithExports);

assert.strictEqual(exportsExp.length, 4, 'must detect 4 export statements');
const expNames = exportsExp.map(e => e.n);
assert.deepStrictEqual(expNames, ['value', 'helper', 'publicAlias', 'default']);

const aliasExport = exportsExp.find(e => e.n === 'publicAlias');
assert.strictEqual(aliasExport.ln, 'localVal', 'local name for alias export must be localVal');

// 4. parse identifies facade re-export modules and distinguishes ESM from plain scripts
const facadeCode = `export * from 'external-lib';`;
const [importsFac, exportsFac, isFacade, hasSyntaxFac] = await parseModule(facadeCode);
assert.strictEqual(importsFac.length, 1);
assert.strictEqual(isFacade, true, 're-export all must be facade');
assert.strictEqual(hasSyntaxFac, true);

const plainScript = `const a = 1; const b = 2; console.log(a + b);`;
const [importsScr, exportsScr, isFacadeScr, hasSyntaxScr] = await parseModule(plainScript);
assert.strictEqual(importsScr.length, 0);
assert.strictEqual(exportsScr.length, 0);
assert.strictEqual(isFacadeScr, false);
assert.strictEqual(hasSyntaxScr, false, 'plain script must have hasModuleSyntax=false');

console.log('All contract assertions passed.');