What does typeof function return in JavaScript?

Table of Contents

• Introduction
• What Does typeof Return?
  • Example: typeof with a Function
    • Example
  • Example: typeof with Different Data Types
• Conclusion

Introduction

In JavaScript, the typeof operator is an essential tool for identifying the type of a given variable or value. This operator can return a variety of type strings, including "function," when applied to functions. Understanding what the typeof function returns is crucial for debugging and ensuring that your code behaves as expected. This guide will clarify what typeof returns when used on functions and other data types, complete with practical examples.

What Does typeof Return?

The typeof operator returns a string that represents the type of the unevaluated operand. Here are the primary type strings that typeof can return:

• "undefined": Indicates that a variable has been declared but has not yet been assigned a value.
• "boolean": Represents the boolean data type (true or false).
• "number": Indicates numeric values, including integers and floats.
• "string": Represents string values (text).
• "object": Refers to object types, including arrays and null.
• "function": Specifically indicates that the operand is a function.

Example: typeof with a Function

When you use the typeof operator on a function, it will return "function".

Example

In this example, myFunction is a function declaration. When typeof is applied to it, the result is "function".

Example: typeof with Different Data Types

To illustrate the versatility of the typeof operator, here are additional examples checking various data types:

Conclusion

The typeof operator in JavaScript is a fundamental tool for checking the type of variables and values, including functions. When applied to a function, it returns the string "function", confirming its type. Understanding the different values returned by typeof will enhance your ability to write clear, robust JavaScript code and effectively debug your applications.