Types

Primitives

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

• string

• number
• boolean
• null
• undefined

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