JavaScript: Return true if the specified value is undefined, false otherwise

JavaScript fundamental (ES6 Syntax): Exercise-185 with Solution

Check If Undefined

Write a JavaScript program that returns true if the specified value is undefined, false otherwise.

Note: Use the strict equality operator to check if the value and of val are equal to undefined.

• Use the strict equality operator to check if val is equal to undefined.

Sample Solution:

JavaScript Code:

// Define a function 'isUndefined' that checks if the value 'val' is strictly equal to undefined
const isUndefined = val => val === undefined;

// Test case to check if the provided value is undefined
console.log(isUndefined(undefined)); // true (the value is undefined)

Output:

true

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-185-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript program that returns true if a given value is strictly equal to undefined.
• Write a JavaScript function that tests an input and returns a boolean indicating whether it is undefined.
• Write a JavaScript program that distinguishes between undefined and null and logs a specific message for each.
• Write a JavaScript function that checks a variable’s type and returns true only if it is undefined.

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