Check Data Types with JavaScript typeof



In this article, you will learn how to check data types with JavaScript typeof.

JavaScript data types

In JavaScript, values ​​are categorized into some data type, and they behave according to each classification.

Below is a list of the main JavaScript data types.

  • Boolean
  • null
  • undefined
  • Number
  • String
  • Object

The typeof operator

In the JavaScript, the typeof operator is used to determine which type a value is classified into.

The syntax is below.

typeof value


typeof true //-> 'boolean'

typeof 123 //-> 'Number'

typeof {name : 'apple'} //-> 'object'

In the actual code, the type is checked by using the condition of the if statement.
Below is sample code to determine if the data type is numeric.

const num1 = 10; //Number
const num2 = '10'; //String

if (typeof num1 === 'number') {
  console.log('The num1 is Number');

if (typeof num2 === 'string') {
  console.log('The num2 is String');