Dynamic Import

Dynamic import: the target is compiled in, but its top-level runs only on the first import, as a task on the program's event loop, and every module it imports is the program's own instance (Node's semantics; see -dynamic-import for the lazy and isolated alternatives).

import { EventEmitter } from 'node:events';

EventEmitter.defaultMaxListeners = 5;
console.log('main: before import');

const first = import('./dynamic_report');
const second = import('./dynamic_report');
console.log('main: import() returned, nothing evaluated yet');

const report = await first;
const again = await second;
console.log('main: report from', report.city, 'sees maxListeners', report.maxListeners);
console.log('main: same module evaluated once:', again.city === report.city);

if (process.argv.length > 99) {
  await import('./dynamic_never');
}
console.log('main: done');

View source on GitHubexamples/imports/dynamic_import.ts

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