JS Practice — Built-in Objects

Object.freeze() — Object.isFrozen returns true

📖 Usage Example

// Make an object immutable
const obj = Object.freeze({ x: 1 })
obj.x = 99   // silently ignored
obj.x        // → 1

Use Object.freeze() to make an object immutable, preventing any additions, deletions, or value changes.

Object.isFrozen()

After freezing, Object.isFrozen(obj) returns true. Unfrozen objects return false.

Challenge: Implement checkFrozen(obj) that freezes obj and returns whether it is frozen.

checkFrozen({ a: 1 }) // → true

💡 Hints (2)

• `Object.isFrozen` returns `true` if the object has been frozen.
• Note that `Object.isFrozen({})` on a pre-frozen empty object may already be `true` in some engines.