Primitives

Work directly on the value when accessing a primitive type.

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

Examples

⇡ Correct code for this rule:

const snow = 1;
let ice = snow;

ice = 9;

console.log(snow, ice); // 1 9

Symbols cannot be faithfully polyfilled, so they should not be used when targeting browsers/environments that don't support them natively.

Complex

Work on a reference to the value when accessing a complex type.

• object
• array
• function

Example

const snow = [1, 2];
const ice = snow;

ice[0] = 9;

console.log(snow[0], ice[0]); // 9 9