JS Built-ins
← GlobalFunctions14 / 40
GlobalFunctionsisNaNintermediate

isNaN — numeric string coerces to number

📖 Usage Example
isNaN('42')           // → false (coerced: Number('42') → 42)
Number.isNaN('42')    // → false

The string '42' coerces to 42, which is not NaN, so isNaN returns false.

isNaN with Numeric String

isNaN('42') coerces '42' to 42 and returns false.

Challenge: Verify the coercion.

💡 Hints (1)
  • • The string '42' coerces to the number 42, which is not NaN.