JavaScript works with different kinds of values, and each value belongs to a specific data type. Understanding data types helps you write cleaner, bug-free code and manage your program’s logic effectively.
In this guide, we’ll explore all JavaScript data types with easy explanations and examples.
⭐ What Are Data Types?
A data type defines the type of value a variable can hold.
JavaScript has two main categories:
✔ Primitive Data Types — simple & immutable
✔ Non-Primitive Data Types — complex & mutable
Let’s look at each in detail.
⭐ Primitive Data Types (7 Types)
Primitive values are stored directly and do not change once created.
JavaScript has 7 primitive data types:
- String
- Number
- Boolean
- Null
- Undefined
- Symbol
- BigInt
✅ 1. String
Used to store text or characters.
Example
let name = "Sagar";
let message = 'Hello World!';
let greeting = `Welcome, ${name}`;
✅ 2. Number
Represents integers and floating-point numbers.
Example
let age = 22;
let price = 99.50;
JavaScript doesn’t differentiate between int, float, or double — everything is a number.
✅ 3. Boolean
Represents logical values — true or false.
Example
let isOnline = true;
let isAdmin = false;
✅ 4. Null
Represents an intentionally empty value.
Example
let data = null; // empty on purpose
✅ 5. Undefined
A variable declared but not assigned a value.
Example
let x;
console.log(x); // undefined
✅ 6. Symbol (ES6)
Unique and immutable values, commonly used as object keys.
Example
let id = Symbol("userID");
✅ 7. BigInt (ES2020)
Used for extremely large numbers beyond the safe integer limit.
Example
let bigNumber = 987654321987654321987654321n;
⭐ Non-Primitive Data Types
JavaScript has one non-primitive type: Object.
Objects can store complex data and multiple values.
Non-primitive types include:
- Objects
- Arrays
- Functions
- Dates
- RegExps
✅ 1. Object
Stores data in key-value pairs.
Example
let user = {
name: "Sagar",
age: 22,
city: "Ludhiana"
};
✅ 2. Array
Stores ordered collections of values.
Example
let fruits = ["Apple", "Banana", "Mango"];
✅ 3. Function
Functions are also treated as objects.
Example
function greet() {
return "Hello!";
}
⭐ Type Checking Using typeof
You can check the type of a value using JavaScript’s typeof operator.
Example
typeof "Hello" // "string"
typeof 42 // "number"
typeof true // "boolean"
typeof undefined // "undefined"
typeof null // "object" // known JS bug
typeof {} // "object"
typeof [] // "object"
typeof function(){} // "function"
⭐ Conclusion
Data types are the foundation of JavaScript programming.
Understanding primitive and non-primitive types helps you manage variables correctly, prevent bugs, and write better code.
📌 Citations
🔗 View other articles about Javascript:
https://savanka.com/category/learn/js/
🔗 External Javascript Documentation:
https://www.w3schools.com/js/