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JavaScript Academy · Lesson

ESM basics — import/export, default vs named

Learn ESM import/export basics: what a module is, named vs default exports, namespace imports, and a light CommonJS contrast.

What is a module?

Goal: Read module syntax with confidence.

  • What a module is
  • Named vs default exports
  • import * as namespace
  • Quick CJS contrast
ESM basics — import/export, default vs named — illustration 1

Module = file + local scope

A module is a file. Its variables are local unless you export them.

// A module is just a file with its own scope
// Here we simulate "module scope" by keeping variables local.
(function () {
  const secret = 42;                          // local to this file/scope
  function reveal() { return "value:" + secret; }
  console.log("module-like scope:", typeof secret === "number", reveal());
})();
ESM basics — import/export, default vs named — illustration 2

All lessons in this course

  1. ESM basics — import/export, default vs named
  2. CommonJS basics — require/module.exports and exports
  3. Module resolution in Node and browser bundlers
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