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# lodash.flattendeep
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lodash.flattendeep provides a standalone implementation of lodash's flattenDeep utility function that recursively flattens nested arrays to any depth. It offers a simple API that takes an array as input and returns a new flattened array, making it ideal for data processing scenarios where nested array structures need to be simplified.
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## Package Information
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- **Package Name**: lodash.flattendeep
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- **Package Type**: npm
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- **Language**: JavaScript
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- **Installation**: `npm install lodash.flattendeep`
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## Core Imports
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```javascript
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var flattenDeep = require('lodash.flattendeep');
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```
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For ES modules:
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```javascript
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import flattenDeep from 'lodash.flattendeep';
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```
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## Basic Usage
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```javascript
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var flattenDeep = require('lodash.flattendeep');
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// Flatten a deeply nested array
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var nestedArray = [1, [2, 3, [4]]];
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var result = flattenDeep(nestedArray);
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console.log(result);
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// => [1, 2, 3, 4]
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// Works with any depth of nesting
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var deeplyNested = [1, [2, [3, [4, [5]]]]];
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var flattened = flattenDeep(deeplyNested);
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console.log(flattened);
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// => [1, 2, 3, 4, 5]
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// Handles empty arrays and mixed types
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var mixedArray = [1, [], [2, [3, []]], 4];
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var mixedResult = flattenDeep(mixedArray);
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console.log(mixedResult);
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// => [1, 2, 3, 4]
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```
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## Capabilities
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### Array Flattening
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Recursively flattens a nested array to any depth, returning a new flat array with all nested elements.
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```javascript { .api }
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/**
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 * Recursively flattens a nested array.
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 * 
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 * @param {Array} array The array to recursively flatten.
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 * @returns {Array} Returns the new flattened array.
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 */
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function flattenDeep(array);
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```
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**Parameters:**
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- `array` (Array): The array to recursively flatten. Can be `null`, `undefined`, or an empty array.
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**Returns:**
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- (Array): Returns the new flattened array. Returns an empty array if the input is falsy or empty.
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**Behavior:**
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- Recursively processes nested arrays to any depth
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- Preserves the order of elements as they appear when traversed depth-first
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- Returns a new array without modifying the original
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- Handles `null` and `undefined` inputs by returning an empty array
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- Preserves non-array elements as-is in their flattened position
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**Usage Examples:**
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```javascript
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var flattenDeep = require('lodash.flattendeep');
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// Basic nested array
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flattenDeep([1, [2, 3, [4]]]);
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// => [1, 2, 3, 4]
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// Deep nesting
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flattenDeep([1, [2, [3, [4, [5, 6]]]]]);
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// => [1, 2, 3, 4, 5, 6]
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// Mixed types
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flattenDeep([1, ['a', [true, [null]]]]);
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// => [1, 'a', true, null]
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// Empty arrays
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flattenDeep([[], [1, []], [2]]);
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// => [1, 2]
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// Null/undefined input
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flattenDeep(null);
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// => []
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flattenDeep(undefined);
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// => []
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// Empty array
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flattenDeep([]);
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// => []
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```