How to use strict inequality In Javascript

Using equality operator with negation

The !== operator checks for both value and type equality, and !== undefined is used to verify if a variable is not equal to the undefined value.

Example: To demonstrate the use of the strict inequality operator by checking whether a number is undefined or not.

Javascript

let num = 5;
 
if (num !== undefined) {
  console.log(num);
} else {
  console.log(undefined);
}

Output

What does !== undefined mean in JavaScript ?

In JavaScript, !== is a strict inequality operator, and undefined is a special value representing the absence of a value or the lack of an assigned value to a variable. The !== operator checks for both value and type equality, and !== undefined is used to verify if a variable is not equal to the undefined value.

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