module in es6 vs commonjs

demo1.md

// es6
export var foo = 'foo';
setTimeout(() => foo = 'baz', 500);

// main
import {foo} from './t.js';
console.log(foo); // foo
setTimeout(() => console.log(foo), 500); // baz

// commonjs
var foo = 'foo'
module.exports = {
  foo: foo
}
setTimeout(() => foo = 'baz', 500);

// main
var foo = require('./t.js').foo
console.log(foo); // foo
setTimeout(() => console.log(foo), 500); // foo

demo2.md

// commonjs
var counter = 3;
function incCounter() {
  counter++;
}
module.exports.counter = counter
module.exports.incCounter = incCounter

var mod = require('./t');

console.log(mod.counter);  // 3
mod.incCounter();
console.log(mod.counter); // 3

// es6
var counter = 3;
function incCounter() {
  counter++;
}
module.exports = {
  get counter() {
    return counter
  },
  incCounter: incCounter,
};

// main
import { counter, incCounter } from './t';
console.log(counter); // 3
incCounter();
console.log(counter); // 4

参考 ES6 模块与 CommonJS 模块的差异