GlobalFunctionsisNaNintermediate

isNaN — undefined coerces to NaN

📖 Usage Example

isNaN(undefined)    // → true
Number(undefined)   // → NaN

undefined coerces to NaN, so the global isNaN(undefined) returns true.

isNaN with undefined

isNaN(undefined) coerces undefined to NaN and returns true.

Challenge: Verify the result.

💡 Hints (1)

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