# Question 3

### Question

How would you implement a custom method to check if an array contains duplicates?

### Answer

```javascript
function hasDuplicates(arr) {
  const seen = new Set(); 

  for (const item of arr) {
    if (seen.has(item)) {
      return true; // Duplicate found!
    }
    seen.add(item);
  }

  return false; // No duplicates found
}

// Example usage:
const array1 = [1, 2, 3, 4, 5];
console.log(hasDuplicates(array1)); // Output: false

const array2 = [1, 2, 3, 2, 4];
console.log(hasDuplicates(array2)); // Output: true
```

**Explanation:**

1. **`seen` Set:** We create a `Set` called `seen`. Sets only store unique values, so they are perfect for checking duplicates.
2. **Iteration:** The code iterates through each item in the input array `arr`.
3. **Duplicate Check:**
   * For every `item`, we check if it's already present in the `seen` set using `seen.has(item)`.
   * If it is, we immediately return `true` because a duplicate has been found.
4. **Adding to `seen`:** If an item isn't already in the `seen` set, we add it using `seen.add(item)` to keep track of encountered values.
5. **No Duplicates:** If the loop completes without finding any duplicates, the function returns `false`.