Types in JS

There are 8 types in JavaScript since ES2020.

The 7 Primitive Types

In JavaScript, values whose types are primitive types are immutable: these values cannot be modified.

Here are the 7 primitive types with examples:

• Undefined (only one value for this type: undefined)
• Null (same, only one value: null)
• Number (42, 0.42, 1e22, Infinity, NaN)
• String ('Blimey!', "Ahoy!", `Aye`, '' - empty string)
• Boolean (true, false)
• Symbol (ES6 - ES2015) (Symbol('Guaranteed unique'))
• BigInt (ES2020) (9007199254740991n)

The Object Type

Any other value is an object. By default, an object is mutable: its properties can be modified, removed, or added. Here are some examples:

• Object ({}, console);
• Function (function () {}, console.log);
• Array (Array) ([], [1, 2, 3]);
• Date (new Date());
• RegExp (/^start.*end$/i);
• Map (new Map());
• Set (new Set());
• ...