NaN and Infinity example in JavaScript

In JavaScript, NaN (Not-a-Number) and Infinity are special numeric values that represent invalid or infinite calculations. Understanding these values is crucial for handling mathematical operations and validation.

What is NaN?

NaN represents a value that is "Not-a-Number". It occurs when a mathematical operation fails or produces an undefined result.

Number("Hello") = NaN
Math.sqrt(-1) = NaN
0 / 0 = NaN
parseInt("abc") = NaN

What is Infinity?

Infinity represents a number greater than any other number. It can be positive or negative.

1 / 0 = Infinity
-1 / 0 = -Infinity
Number.POSITIVE_INFINITY = Infinity
Number.NEGATIVE_INFINITY = -Infinity

Checking for NaN and Infinity

JavaScript provides built-in functions to detect these special values:

isNaN(NaN) = true
Number.isNaN(NaN) = true
isFinite(Infinity) = false
Number.isFinite(Infinity) = false

Key Differences

Conclusion

NaN occurs from invalid operations while Infinity results from division by zero. Use Number.isNaN() and Number.isFinite() to properly detect these special values in your applications.