Which is the correct syntax of JavaScript typeof operator?

Table of Contents

• Introduction
• Correct Syntax of typeof Operator
• Usage Examples
  • 1. Checking the Type of a Variable
  • 2. Checking the Type of a Number
  • 3. Checking for Undefined Variables
  • 4. Checking the Type of a Boolean Value
• Conclusion

Introduction

The typeof operator in JavaScript is used to determine the data type of a given variable or expression. It returns a string representing the type of the operand. Knowing the correct syntax and usage of typeof is crucial for writing effective JavaScript code.

Correct Syntax of typeof Operator

The correct syntax for using the typeof operator in JavaScript is as follows:

• operand: This can be a variable, expression, or value whose data type you want to check.
• Returns: A string indicating the type of the operand.

Usage Examples

1. Checking the Type of a Variable

You can use typeof to determine the type of a variable and handle it accordingly.

Example:

2. Checking the Type of a Number

3. Checking for Undefined Variables

Using typeof to check whether a variable is defined or not avoids runtime errors.

4. Checking the Type of a Boolean Value

Conclusion

The typeof operator is simple and effective for type checking in JavaScript. Its correct syntax is typeof operand, and it returns the data type as a string. Whether you're checking the type of a string, number, boolean, or even an undefined variable, typeof is a useful tool for ensuring your code operates as expected.