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## Short answer:

```javascript
const arr = [10, 20, 30];
delete arr[0];

console.log(arr);       // [ <1 empty item>, 20, 30 ]
console.log(arr.length); // 3
```

The element at index `0` **gets deleted**,
but its slot stays **empty** - the array's length **does not change**.

## What happens "under the hood"

- `delete` **removes a property** from an object (and an array is an object with numeric keys).
- It does not shift the remaining elements, and it does not change `length`.
- As a result, a **"hole"** appears in the array - the so-called *empty slot*.

## Demonstration:

```javascript
const arr = [1, 2, 3];
delete arr[1];

console.log(arr);        // [1, <1 empty item>, 3]
console.log(arr.length); // 3
console.log(1 in arr);   // false - the element genuinely doesn't exist
```

## Why this is not recommended

These "empty cells" behave strangely:

- `forEach`, `map`, `filter` and other methods **skip** them:

```javascript
  arr.forEach(el => console.log(el)); // prints only 1 and 3
  ```
- But direct access (`arr[1]`) returns `undefined`.

## The correct way to remove an element

Use `splice()` if you need to shift the remaining elements:

```javascript
const arr = [10, 20, 30];
arr.splice(0, 1);

console.log(arr);       // [20, 30]
console.log(arr.length); // 2
```

## Briefly:

| Method | What it does | Changes length | Creates a "hole"? |
| --- | --- | --- | --- |
| `delete arr[i]` | removes a property | No | Yes |
| `arr.splice(i, 1)` | removes an element and shifts | Yes | No |

> **Conclusion:**
> It is better not to use `delete arr[index]` for arrays -
> it leaves "empty slots" and makes the structure "ragged".
> Use `splice()` for safe removal.

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