For use in CommonJS:

const { parse } = require('cjs-module-lexer');

const { exports, reexports } = parse(`

Spacing between tokens is taken to be any ECMA-262 whitespace, ECMA-262 block comment or ECMA-262 line comment.

* The returned export names are taken to be the combination of:

1. All `IDENTIFIER` and `IDENTIFIER_STRING` slots for `EXPORTS_MEMBER` and `EXPORTS_LITERAL` matches.

2. The first `IDENTIFIER_STRING` slot for all `EXPORTS_DEFINE_VALUE` matches where that same string is not an `EXPORTS_DEFINE` match that is not also an `EXPORTS_DEFINE_VALUE` match.

* The reexport specifiers are taken to be the the combination of:

1. The `REQUIRE` matches of the last matched of either `MODULE_EXPORTS_ASSIGN` or `EXPORTS_LITERAL`.

2. All _top-level_ `EXPORT_STAR` `REQUIRE` matches and `EXPORTS_ASSIGN` matches whose `IDENTIFIER` also matches the first `IDENTIFIER` in `EXPORT_STAR_LIB`.

})(exports);

`Object.defineProperty` is detected for specifically value and getter forms returning an identifier or member expression:

Object.defineProperty(exports, '__esModule', { value: true });

To avoid matching getters that have side effects, any getter for an export name that does not support the forms above will

opt-out of the getter matching:

Object.defineProperty(exports, 'a', {

value: 'no problem'

});

if (false) {

Object.defineProperty(module.exports, 'a', {

get () {

return dynamic();

}

})

}

Alternative object definition structures or getter function bodies are not detected:

Wasm Build:

starExportMap,

lastStarExportSpecifier,

_exports,

unsafeGetters,

reexports;

function resetState () {

lastStarExportSpecifier = null;

_exports = new Set();

unsafeGetters = new Set();

reexports = new Set();

const strictReserved = new Set(['implements', 'interface', 'let', 'package', 'private', 'protected', 'public', 'static', 'yield', 'enum']);

function parseCJS (source, name = '@') {

resetState();

try {

parseSource(source);

e.loc = pos;

throw e;

}

const result = { exports: [..._exports].filter(expt => !unsafeGetters.has(expt)), reexports: [...reexports] };

resetState();

return result;

pos++;

ch = commentWhitespace();

if (ch === 100/*d*/ && source.startsWith('efineProperty', pos + 1)) {

let expt;

while (true) {

pos += 14;

revertPos = pos - 1;

let quot = ch;

const exportPos = ++pos;

if (!identifier() || source.charCodeAt(pos) !== quot) break;

expt = source.slice(exportPos, pos);

pos++;

ch = commentWhitespace();

if (ch !== 44/*,*/) break;

pos += 5;

ch = commentWhitespace();

if (ch !== 58/*:*/) break;

addExport(expt);

pos = revertPos;

return;

}

else if (ch === 103/*g*/) {

if (!source.startsWith('et', pos + 1)) break;

}

break;

}

if (expt) {

unsafeGetters.add(expt);

}

}

else if (keys && ch === 107/*k*/ && source.startsWith('eys', pos + 1)) {

while (true) {

case 46/*.*/:

throw new Error('Unexpected import.meta in CJS module.');

return;

default:

// no space after "import" -> not an import keyword

if (pos === startPos + 6)

function readPrecedingKeyword1 (pos, ch) {

return source.charCodeAt(pos) === ch && (pos === 0 || isBrOrWsOrPunctuatorNotDot(source.charCodeAt(pos - 1)));

// throw

return readPrecedingKeyword(pos - 2, 'thr');

default:

return false;

}

}

return false;

}

return false;

const initPromise = Promise.resolve();

module.exports.init = () => initPromise;

module.exports.parse = parseCJS;

{

"name": "cjs-module-lexer",

"version": "1.0.0",

"description": "Lexes CommonJS modules, returning their named exports metadata",

"main": "lexer.js",

"exports": {

"import": "./dist/lexer.mjs",

"default": "./lexer.js"

},

"types": "lexer.d.ts",

"scripts": {

"test-js": "mocha -b -u tdd test/*.js",

"test-wasm": "WASM=1 mocha -b -u tdd test/*.js",

"terser": "^4.1.4"

},

"files": [

"dist",

"lexer.d.ts"

],

"repository": {

"type": "git",

[`Uint8Array`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array

[dynamic instantiate hook]: #esm_code_dynamicinstantiate_code_hook

[`util.TextDecoder`]: util.md#util_class_util_textdecoder

[cjs-module-lexer]: https://github.com/guybedford/cjs-module-lexer/tree/1.0.0

[special scheme]: https://url.spec.whatwg.org/#special-scheme

[the official standard format]: https://tc39.github.io/ecma262/#sec-modules

[transpiler loader example]: #esm_transpiler_loader

let cjsParse;

async function initCJSParse() {

if (typeof WebAssembly === 'undefined') {

cjsParse = require('internal/deps/cjs-module-lexer/lexer').parse;

} else {

const { parse, init } =

require('internal/deps/cjs-module-lexer/dist/lexer');