typeof operator

The typeof operator is used to determine the type of a value or variable. It returns a string indicating the type of the operand.

Syntax

The syntax of the typeof operator is as follows:

1typeof operand

Usage

The typeof operator can be used with different types of operands.

Here are some examples:

1. Checking the type of a variable:

   1let username = "John";
   2console.log(typeof username); // Output: "string"
   

2. Checking the type of a numeric value:

   1console.log(typeof 42); // Output: "number"
   

3. Checking the type of a boolean expression:

   1let isActive = true;
   2console.log(typeof true); // Output: "boolean"
   

4. Checking the type of an undefined value:

   1let age;
   2console.log(typeof age); // Output: "undefined"
   

The typeof operator is a useful tool in JavaScript for determining the type of a value or variable. It returns a string representing the data type of the operand.

Understanding the type of data can help in writing more robust and error-free code.