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## 1. `Array.isArray(value)` - the modern and reliable way

```javascript
Array.isArray([1, 2, 3]); // true
Array.isArray("text");    // false
Array.isArray({});        // false
```

- Works in all modern browsers and Node.js.
- Correctly identifies arrays even from **other contexts** (for example, from an iframe).
- This is the **recommended** way to check.

---

## 2. `instanceof Array` - old, but functional

```javascript
[1, 2, 3] instanceof Array; // true
"abc" instanceof Array;     // false
```

However:

- If the array was created in **another window or frame**, the result can be **false**, because each context has its own `Array` constructor.

```javascript
// Example of the problem:
const arr = window.frames[0].Array;
arr instanceof Array; // false
```

---

## 3. Checking via `Object.prototype.toString.call()`

This method is universal for any type (often used in libraries).

```javascript
Object.prototype.toString.call([]); // "[object Array]"
Object.prototype.toString.call({}); // "[object Object]"
Object.prototype.toString.call("hi"); // "[object String]"
```

---

## 4. Why not `typeof`

```javascript
typeof []; // "object"
```

`typeof` does not work because an array is an **object**, and the result is always `"object"`.

---

## Summary

| Method | Returns | Reliability | Comment |
|---|---|---|---|
| `Array.isArray(value)` | correct | 5/5 | the best option |
| `value instanceof Array` | correct | 3/5 | depends on context |
| `Object.prototype.toString.call(value)` | correct | 4/5 | universal, but bulky |
| `typeof value` | `"object"` | 1/5 | does not distinguish arrays |

---

> **Conclusion:**
> Always use `Array.isArray(value)` - it is the most accurate and shortest way.

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