Suggest an edit

Improve this article

Refine the answer for “typeof []”. Your changes go to moderation before they’re published.

Approval required

Content

What you’re changing

Title (EN)

Short answer (EN)

Shown above the full answer for quick recall.

Answer (EN)

The `typeof` operator in JavaScript returns **the type of a value** as a string.
But it has one **non-obvious behavior** - with arrays.

---

## Example:

```javascript
console.log(typeof []); // "object"
```

Yes, an array returns `"object"` - **not** `"array"`.

---

## Why is that?

Because in JavaScript **an array is a special case of an object**.
Internally it is implemented as an object, where:

- the **keys** are numeric indexes (`"0"`, `"1"`, `"2"`),
- and the `length` property tracks the number of elements.

Example:

```javascript
const arr = ["a", "b"];
console.log(Object.keys(arr)); // ["0", "1"]
```

---

## How to correctly check that it is actually an array

Use:

```javascript
Array.isArray([]);
```

```javascript
[] instanceof Array;
```

Both options return:

```javascript
true
```

---

## In short:

| Check | Returns | Comment |
|---|---|---|
| `typeof []` | `"object"` | because an array is an object |
| `Array.isArray([])` | `true` | the correct way |
| `[] instanceof Array` | `true` | also correct, but depends on the environment |

---

> **Summary:**
> `typeof []` -> `"object"`
> because arrays are **special objects**, optimized for storing ordered data.

Markdown · drag & drop images · ⌘B / ⌘I shortcuts192 words

For the reviewer

Note to the moderator (optional)

Visible only to the moderator. Helps review go faster.