Datatypes

In JavaScript, the type of the data can be classified into 2 types. They are

• Primitive
• Non-Primitive

Primitive data types

There are 6 primitive data types in JavaScript:

• Number
• String
• Boolean
• Null
• Undefined
• Symbol

Number

In JavaScript, the number data type can represent both integer as well as decimal numbers.

Example

let avg = 34.84; // decimal number  
let age = 35; // integer number

We can also represent large or small numbrs with scientific notation.

Example

let x = 123e4; // 1230000  
let y = 123e-4; // 0.0123

String

In JavaScript, string is the series of characters enclosed in double quotes.

Example

let name = "ReadersBuddy";

Boolean

Boolean variable can have one of the two values: true or false. This type is used to store only true or false values.

Example

let isEmployee = true;

Null

In JavaScript, null means nothing or empty. If we need to set a value to empty, then we can use the null value.
The data type of null is an object.

Example

let salary = null;
console.log(typeof salary);      // object

Undefined

In JavaScript, a variable without a value is always undefined. The value undefined means ???value is not assigned???.

Example

let salary;
console.log(salary); // undefined

Symbol

The JavaScript ES6 introduced a new primitive data type called Symbol. Symbols are immutable (cannot be changed) and are unique.

Example

// two symbols with the same description
const item1 = Symbol('hi');
const item2 = Symbol('hi');

console.log(item1 === item2); // false

Though item1 and item2 both contains the same value, they are considered different.

Accessing Symbol
To access the symbol description, we use description property with (.) operator.

Example

const name = Symbol('ReadersBuddy');
console.log(name.description); // ReadersBuddy