Primitive types

Learn the primitive types string, number, boolean, null, undefined.

Primitive types

In JavaScript, primitive types are the most basic data types: number, string, boolean, null and undefined. They hold a single value and are not objects.

number holds both integers and decimals. string holds text. boolean is only true or false.

null means 'intentionally empty', undefined means 'value not yet assigned'. They are different things.

Five primitive types

Let us briefly meet each of the five primitives:

number: 42, 3.14
string: 'hello', "world"
boolean: true, false
null: intentionally empty value
undefined: not yet assigned value

We will see these in detail later. For now, knowing all five is enough.

Exercise Print three different primitives

Declare three variables: name string 'Alex', count number 7, active boolean true. Call console.log with each.

Show example solution

const name = "Alex";
const count = 7;
const active = true;
console.log(name);
console.log(count);
console.log(active);

Test yourself

Which one is a primitive type?
- Array
- Number
- Object
- Function
Show answer

Number — number is a primitive type.

boolean example

const isOpen = ____;

Show answer

const isOpen = true;

Match the primitive types

number

Number
string

Text
boolean

Logical
undefined

Not defined

Next lesson: Template literals

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