JS Practice — Built-in Objects

Set size — deduplication

📖 Usage Example

const s = new Set([1, 2, 3])
console.log(s.size)   // → 3
s.add(4)
console.log(s.size)   // → 4

Read Set.size to get the number of unique values in the set.

Set.prototype.size

Adding the same value twice keeps size at 1.

Challenge: Verify that adding a duplicate doesn't increase size.

💡 Hints (1)