JS Practice — Built-in Objects

Object.is() — null equals null

📖 Usage Example

// Strict identity that handles edge cases
Object.is(NaN, NaN)   // → true  (unlike ===)
Object.is(0, -0)      // → false (unlike ===)
Object.is(1, 1)       // → true

Use Object.is() for strict value comparison that correctly handles NaN equality and distinguishes +0 from -0.

Object.is() — null and undefined

Object.is(null, null) returns true. Object.is(null, undefined) returns false — unlike loose equality null == undefined.

Challenge: Implement checkNull() that returns Object.is(null, null).

checkNull()            // → true
null == undefined      // → true  (loose equality)
Object.is(null, undefined) // → false (strict same-value)

💡 Hints (2)

• `Object.is` is stricter than `==` — it never coerces types.
• `null == undefined` is true (loose), but `Object.is(null, undefined)` is false.