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# Lodash Sum
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Lodash Sum provides the `_.sum` method exported as a standalone Node.js module. It computes the sum of all values in an array with robust handling of edge cases like empty arrays and undefined values.
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## Package Information
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- **Package Name**: lodash.sum
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- **Package Type**: npm
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- **Language**: JavaScript
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- **Installation**: `npm install lodash.sum`
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## Core Imports
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```javascript
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const sum = require('lodash.sum');
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```
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For ES modules environments (CommonJS package):
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```javascript
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import sum from 'lodash.sum';
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```
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## Basic Usage
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```javascript
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const sum = require('lodash.sum');
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// Basic array summation
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const result = sum([4, 2, 8, 6]);
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console.log(result); // => 20
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// Handle empty arrays
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const empty = sum([]);
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console.log(empty); // => 0
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// Handle null/undefined input
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const nullResult = sum(null);
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console.log(nullResult); // => 0
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```
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## Capabilities
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### Array Summation
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Computes the sum of all values in an array, handling edge cases gracefully.
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```javascript { .api }
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/**
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 * Computes the sum of the values in `array`.
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 *
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 * @static
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 * @memberOf _
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 * @since 3.4.0
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 * @category Math
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 * @param {Array} array The array to iterate over.
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 * @returns {number} Returns the sum.
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 * @example
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 *
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 * _.sum([4, 2, 8, 6]);
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 * // => 20
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 */
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function sum(array);
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```
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**Behavior Details:**
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- **Empty arrays**: Returns `0`
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- **Falsy input**: Any falsy value (null, undefined, false, 0, "", etc.) returns `0`
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- **Undefined array elements**: Skipped during summation (not included in result)
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- **Non-numeric values**: Processed through JavaScript's automatic type coercion during addition
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- **Type**: Pure function with no side effects
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**Usage Examples:**
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```javascript
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const sum = require('lodash.sum');
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// Numeric arrays
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sum([1, 2, 3, 4, 5]); // => 15
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sum([10.5, 20.25, 5.75]); // => 36.5
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// Arrays with mixed types (numeric coercion applies)
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sum([1, '2', 3]); // => 6
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sum(['10', '20', '30']); // => 60
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// Edge cases
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sum([]); // => 0
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sum([undefined, 1, 2]); // => 3 (undefined elements are skipped)
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sum([1, , 3]); // => 4 (sparse array holes become undefined, are skipped)
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sum(null); // => 0
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sum(undefined); // => 0
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sum(false); // => 0
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sum(0); // => 0
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// Single value arrays
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sum([42]); // => 42
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sum([0]); // => 0
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sum([-5, 5]); // => 0
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```
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## Error Handling
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The `sum` function is designed to be robust and does not throw errors under normal usage:
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- Any falsy input (null, undefined, false, 0, "", NaN) returns `0`
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- Arrays containing undefined elements skip those elements during summation
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- Non-numeric array elements undergo JavaScript's automatic type coercion during addition
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- No input validation or type checking is performed - the function relies on JavaScript's truthy/falsy evaluation