Detecting Undefined Values in JavaScript

JavaScript's undefined value represents a variable that has been declared but has not been assigned a value. Accurately identifying undefined is crucial for robust error handling, preventing unexpected behavior, and ensuring your code functions correctly when dealing with potentially missing data. This challenge will test your ability to reliably check for undefined values in various scenarios.

Problem Description

You are tasked with creating a JavaScript function called isUndefined that takes a single argument, value, and returns true if the value is strictly equal to undefined. The function should return false otherwise. Strict equality (===) is essential to avoid type coercion issues.

Key Requirements:

• The function must be named isUndefined.
• It must accept a single argument, value.
• It must return a boolean value (true or false).
• It must use strict equality (===) to compare the input value with undefined.

Expected Behavior:

The function should correctly identify undefined values regardless of their origin (e.g., uninitialized variables, function return values). It should also correctly handle other data types and values that are not undefined.

Edge Cases to Consider:

• null: null is not undefined. The function should return false for null.
• Empty string (""): An empty string is not undefined. The function should return false for an empty string.
• Zero (0): Zero is not undefined. The function should return false for zero.
• false: false is not undefined. The function should return false for false.
• Objects: Objects are not undefined. The function should return false for objects.
• Arrays: Arrays are not undefined. The function should return false for arrays.
• Functions: Functions are not undefined. The function should return false for functions.

Examples

Example 1:

Input: undefined
Output: true
Explanation: The input is directly the undefined value.

Example 2:

Input: null
Output: false
Explanation: null is a distinct value from undefined.

Example 3:

Input: 0
Output: false
Explanation: 0 is a number, not undefined.

Example 4:

Input: ""
Output: false
Explanation: An empty string is a valid string value, not undefined.

Example 5:

Input: { name: "John" }
Output: false
Explanation: An object is not undefined.

Constraints

• The function must be written in JavaScript.
• The function must only accept a single argument.
• The function must return a boolean value.
• The function must use strict equality (===).
• The input value can be of any JavaScript data type.

Notes

Consider the importance of strict equality (===) in JavaScript. Using loose equality (==) can lead to unexpected results due to type coercion. Think about how different data types behave when compared to undefined. A simple if (value === undefined) is the core of the solution, but ensuring you understand why this is the correct approach is key.