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NodeJS ES Module Loader

Loads ES modules and WebAssembly with CJS interop in Node, roughly according to

WASM support is currently only provided for Node 8 nightly.

Follows the NodeJS resolution algorithm, loading modules first as CJS and then falling back to ES on import or export syntax failures. This effectively provides the "export {}" assumption to load an ES module.

This does mean a double-parse, over the mjs approach currently being taken by Node.

Built with the ES Module Loader polyfill 1.0 branch at


npm install -g node-es-module-loader


Execute an ES module file:

node-esml module.js

For example, where module.js contains:

import fs from 'fs';
import {fn} from './local-es-module.js';
import {wasmFn} from './local-wasm-binary.wasm';

Note that only the default import form for CommonJS modules is supported.

Also supports dynamic loading via the dynamic import syntax:

export function lazyLoad(path) {
  return import(path);

Source maps for errors are fully supported through the source-map-support project.

Source maps also work in Node 6 with the node --inspect flag via:

node --inspect node_modules/.bin/node-esml module.js

Programmatic Usage

var NodeESModuleLoader = require('node-es-module-loader');
var loader = new NodeESModuleLoader(/* optional basePath */);
loader.import('x').then(function(m) {
  // ... 


Alternative Babel options can be set with a local .babelrc file.