Data Types in JavaScript

Every value in JavaScript has a data type. Understanding types is essential for writing correct and predictable code.

JavaScript has two main categories: primitive types (immutable basic values) and objects (complex, mutable data).

Primitive Types

There are seven primitive data types:

• String – text values
• Number – integers and floating-point numbers
• Boolean – true or false
• Undefined – variable declared but not assigned
• Null – intentional absence of value
• Symbol – unique identifiers (ES6)
• BigInt – arbitrary-precision integers (ES2020)

String

Number

JavaScript has one number type for both integers and floats.

Boolean

Undefined and Null

Symbol and BigInt

Objects

Everything else (arrays, functions, dates, etc.) is an object.

Checking Types with typeof

Quick Quiz