JS Practice — Built-in Objects

Number.isNaN() — '1' (string) returns false, unlike global isNaN

📖 Usage Example

// Check for NaN without coercion
Number.isNaN(NaN)    // → true
Number.isNaN('NaN')  // → false (no coercion)
Number.isNaN(42)     // → false

Use Number.isNaN() instead of the global isNaN() to check for NaN without coercing the argument first.

Number.isNaN() vs global isNaN — Strings

isNaN('hello') returns true (coerces string to NaN). Number.isNaN('hello') returns false (no coercion).

💡 Hints (1)

• `Number.isNaN` never coerces — it only returns `true` for the actual `NaN` value.