1. Types

1.1 primitives (원시타입)

When you access a primitive type you work directly on its value.

• string
• number
• boolean
• null
• undefined
• symbol
• bigint

const foo = 1;
let bar = foo;

bar = 9;

console.log(foo, bar); // => 1, 9

Complex

When you access a complex type you work on a reference to its value.

• object
• array
• function

const foo = [1, 2];
const bar = foo;

bar[0] = 9;

console.log(foo[0], bar[0]); // => 9, 9

출처 : https://github.com/airbnb/javascript