How to Use the Nan Condition in JavaScript?

The value NaN (Not-A-Number) in JavaScript represents a value that is not a number. It is used to represent the result of an invalid mathematical operation, such as dividing 0 by 0 or trying to parse a string as a number when the string cannot be converted to a number.

You can use the isNaN function in JavaScript to check if a value is NaN:

var result = 0/0;
if (isNaN(result)) {
  console.log("The result is Not-A-Number");
} else {
  console.log("The result is a number");
}
// Output: The result is Not-A-Number

In the example above, the isNaN function is used to check if the value of result is NaN. If the value of result is NaN, then the message “The result is Not-A-Number” is logged to the console. Otherwise, the message “The result is a number” is logged to the console.

It’s important to note that isNaN has a number of gotchas and may not always behave as expected. For example, isNaN will return true for non-numeric values, such as null or undefined. If you need to check if a value is a number, it’s usually a better idea to use typeof and compare the result to the string “number”:

var result = 0/0;
if (typeof result === "number") {
  console.log("The result is a number");
} else {
  console.log("The result is not a number");
}
// Output: The result is a number