I have the following import mongo from "mongodb"; I would like to avoid using npm and instead use unpkg.com like this import mongo from "https://unpkg.com/mongodb";. However, when I run I get...
...@penguin:~/...$ node --harmony test.mjs node:internal/process/esm_loader:74
internalBinding('errors').triggerUncaughtException(
^
Error [ERR_UNSUPPORTED_ESM_URL_SCHEME]: Only file and data URLs are supported by the default ESM loader. Received protocol 'https:'
at new NodeError (node:internal/errors:328:5)
at Loader.defaultResolve [as _resolve] (node:internal/modules/esm/resolve:825:11)
at Loader.resolve (node:internal/modules/esm/loader:86:40)
at Loader.getModuleJob (node:internal/modules/esm/loader:230:28)
at ModuleWrap.<anonymous> (node:internal/modules/esm/module_job:56:40)
at link (node:internal/modules/esm/module_job:55:36) {
code: 'ERR_UNSUPPORTED_ESM_URL_SCHEME'
}
Because it uses the term default module loader I was wondering if there was an alternative ESM loader I could use.
Node will eventually support ESM URL imports: https://github.com/nodejs/node/pull/36328. This feature is currently available under a CLI flag --experimental-https-modules. It doesn't ship with public releases yet (as of Node 17.8.0), so you will need to build Node from source for this as of current.
In the meanwhile, Node has experimental support for module loaders and even shows a HTTPS loader as an example:
https://nodejs.org/api/esm.html#esm_https_loader
// https-loader.mjs
import { get } from 'https';
export function resolve(specifier, context, defaultResolve) {
const { parentURL = null } = context;
// Normally Node.js would error on specifiers starting with 'https://', so
// this hook intercepts them and converts them into absolute URLs to be
// passed along to the later hooks below.
if (specifier.startsWith('https://')) {
return {
url: specifier
};
} else if (parentURL && parentURL.startsWith('https://')) {
return {
url: new URL(specifier, parentURL).href
};
}
// Let Node.js handle all other specifiers.
return defaultResolve(specifier, context, defaultResolve);
}
export function load(url, context, defaultLoad) {
// For JavaScript to be loaded over the network, we need to fetch and
// return it.
if (url.startsWith('https://')) {
return new Promise((resolve, reject) => {
get(url, (res) => {
let data = '';
res.on('data', (chunk) => data += chunk);
res.on('end', () => resolve({
// This example assumes all network-provided JavaScript is ES module
// code.
format: 'module',
source: data,
}));
}).on('error', (err) => reject(err));
});
}
// Let Node.js handle all other URLs.
return defaultLoad(url, context, defaultLoad);
}
Use like so:
node --experimental-loader ./https-loader.mjs ./main.mjs