:lib.js// 定義
export const title = 'ES Modules'
function square(x) {
return x * x
}
const num = Math.E + Math.PI
export { square, num }app.js// 読み込み
import { square, num } from './lib'
console.log(square(4)) // 16
console.log(num) // 5.859874482048838