NaN

NaN means Not-A-Number. Let's see examples of NaN:

NaN is typically used in conjuction with conditional statements to handle number scenarios.

Here is a quick example of how to implement NaN:

info

'1' is a number, so isNaN() is false hence returns '1'.

But 'stringhere' is clearly not a number hence returns NaN

Here are some operations that return NaN:

• Failed number conversion (as in Number(undefined), or implicitly Math.abs(undefined))

• Math operation where the result is not real (e.g. Math.sqrt(-5))

• Indeterminate forms: (0 * infinity, 1 ** infinity1, etc)

• A method/expression whose operand gets coerced to NaN: (7 ** NaN, 7 * "word")

  • (NaN is contagious)

• Cases where an invalid value is represented as a number (new Date("word".getTime()))

To test if something is NaN, one can use Number.isNaN(), otherwise there is isNaN().

tip

Be careful for NaN values and make sure to check for them in try...catch methods or throw exceptions.

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