JavaScript Null Check

In JavaScript development, it's common to encounter situations where a variable might not have a defined value, leading to potential errors. Robustly checking for null is a fundamental skill that prevents unexpected behavior and ensures your code functions correctly. This challenge will help you practice identifying and handling null values.

Problem Description

Your task is to write a JavaScript function that takes a single argument and returns true if the argument is strictly null, and false otherwise.

Key Requirements:

• The function must be named isNull.
• The function should accept one argument of any data type.
• The function must return a boolean value: true if the argument is null, false if it's anything else.

Expected Behavior:

• If the input is the primitive value null, the function should return true.
• If the input is undefined, a string, a number, a boolean, an object, an array, or any other JavaScript value, the function should return false.

Edge Cases to Consider:

• undefined: This is a common point of confusion with null. Your function should differentiate between the two.
• 0, false, '' (empty string): These are falsy values but are not null.

Examples

Example 1:

Input: null
Output: true
Explanation: The input is the primitive value `null`, so the function correctly returns `true`.

Example 2:

Input: undefined
Output: false
Explanation: The input is `undefined`, which is distinct from `null`. The function returns `false`.

Example 3:

Input: "hello"
Output: false
Explanation: The input is a string, not `null`. The function returns `false`.

Example 4:

Input: 0
Output: false
Explanation: The input is the number `0`, which is a falsy value but not `null`. The function returns `false`.

Example 5:

Input: {}
Output: false
Explanation: The input is an empty object, not `null`. The function returns `false`.

Constraints

• The function must be implemented in JavaScript.
• The solution should be efficient and avoid unnecessary operations.
• No external libraries or frameworks are allowed.

Notes

Remember that in JavaScript, null and undefined are different. The strict equality operator (===) is your best friend here, as it checks for both value and type without performing type coercion. Consider how === behaves when comparing null to other values.