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# isarray
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A lightweight polyfill that provides `Array.isArray` functionality for older browsers and deprecated Node.js versions. Uses native `Array.isArray` when available, falls back to `Object.prototype.toString.call()` method when not available.
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## Package Information
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- **Package Name**: isarray
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- **Package Type**: npm
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- **Language**: JavaScript
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- **Installation**: `npm install isarray`
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## Core Imports
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```javascript
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var isArray = require('isarray');
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```
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For ES modules (CommonJS interop):
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```javascript
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import isArray from 'isarray';
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```
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## Basic Usage
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```javascript
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var isArray = require('isarray');
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console.log(isArray([])); // => true
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console.log(isArray({})); // => false
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console.log(isArray(null)); // => false
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console.log(isArray('[]')); // => false
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// Works with arrays that have additional properties
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var arr = [];
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arr.foo = 'bar';
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console.log(isArray(arr)); // => true
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// Returns false for array-like objects
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var obj = {};
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obj[0] = true;
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console.log(isArray(obj)); // => false
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```
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## Capabilities
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### Array Detection
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Determines whether the passed value is an Array.
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```javascript { .api }
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/**
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 * Determines whether the passed value is an Array
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 * @param {*} arr - The value to be checked
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 * @returns {boolean} Returns true if the value is an Array, false otherwise
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 */
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function isArray(arr);
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```
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**Parameters:**
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- `arr` (any): The value to be checked
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**Returns:**
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- `boolean`: Returns `true` if the value is an Array, `false` otherwise
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**Implementation Details:**
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- Uses native `Array.isArray` when available (modern environments)
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- Falls back to `Object.prototype.toString.call(arr) == '[object Array]'` for older environments
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- Works consistently across both native and polyfill implementations
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- Handles edge cases like arrays with additional properties correctly
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**Browser Compatibility:**
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- Internet Explorer 8+
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- Firefox 17+
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- Chrome 22+
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- Opera 12+
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- Safari 5.1+
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- Mobile browsers (iOS 6.0+, Android 4.2+)
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**Usage Examples:**
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```javascript
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var isArray = require('isarray');
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// Basic type checking
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console.log(isArray([])); // => true
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console.log(isArray([1, 2, 3])); // => true
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console.log(isArray({})); // => false
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console.log(isArray(null)); // => false
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console.log(isArray(undefined)); // => false
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console.log(isArray('string')); // => false
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console.log(isArray(42)); // => false
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console.log(isArray(function(){})); // => false
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// Edge cases
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console.log(isArray('[]')); // => false (string, not array)
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console.log(isArray(document.querySelectorAll('div'))); // => false (NodeList, not array)
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// Arrays with properties
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var arr = [1, 2, 3];
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arr.customProperty = 'value';
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console.log(isArray(arr)); // => true
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// Array-like objects
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var arrayLike = { 0: 'a', 1: 'b', length: 2 };
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console.log(isArray(arrayLike)); // => false
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```
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## Migration Note
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**For modern environments:** The documentation explicitly recommends using native `Array.isArray` directly instead of this polyfill when targeting modern browsers and Node.js versions that support it natively.
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```javascript
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// Modern approach (when IE8 support not needed)
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console.log(Array.isArray([])); // => true
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// Polyfill approach (for IE8 and older Node.js versions)
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var isArray = require('isarray');
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console.log(isArray([])); // => true
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```