lts/lib/internal/process/esm_loader.js
'use strict';
const {
ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING,
} = require('internal/errors').codes;
const assert = require('internal/assert');
const { Loader } = require('internal/modules/esm/loader');
const { pathToFileURL } = require('internal/url');
const {
getModuleFromWrap,
} = require('internal/vm/module');
const { getOptionValue } = require('internal/options');
const userLoader = getOptionValue('--experimental-loader');
exports.initializeImportMetaObject = function(wrap, meta) {
const { callbackMap } = internalBinding('module_wrap');
if (callbackMap.has(wrap)) {
const { initializeImportMeta } = callbackMap.get(wrap);
if (initializeImportMeta !== undefined) {
initializeImportMeta(meta, getModuleFromWrap(wrap) || wrap);
}
}
};
exports.importModuleDynamicallyCallback = async function(wrap, specifier) {
assert(calledInitialize === true || !userLoader);
if (!calledInitialize) {
process.emitWarning(
'The ESM module loader is experimental.',
'ExperimentalWarning', undefined);
calledInitialize = true;
}
const { callbackMap } = internalBinding('module_wrap');
if (callbackMap.has(wrap)) {
const { importModuleDynamically } = callbackMap.get(wrap);
if (importModuleDynamically !== undefined) {
return importModuleDynamically(
specifier, getModuleFromWrap(wrap) || wrap);
}
}
throw new ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING();
};
let ESMLoader = new Loader();
exports.ESMLoader = ESMLoader;
let calledInitialize = false;
exports.initializeLoader = initializeLoader;
async function initializeLoader() {
assert(calledInitialize === false);
process.emitWarning(
'The ESM module loader is experimental.',
'ExperimentalWarning', undefined);
calledInitialize = true;
if (!userLoader)
return;
let cwd;
try {
cwd = process.cwd() + '/';
} catch {
cwd = 'file:///';
}
// If --experimental-loader is specified, create a loader with user hooks.
// Otherwise create the default loader.
const { emitExperimentalWarning } = require('internal/util');
emitExperimentalWarning('--experimental-loader');
return (async () => {
const hooks =
await ESMLoader.import(userLoader, pathToFileURL(cwd).href);
ESMLoader = new Loader();
ESMLoader.hook(hooks);
ESMLoader.runGlobalPreloadCode();
return exports.ESMLoader = ESMLoader;
})();
}