npm-lodash

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# Lodash
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Lodash is a modern JavaScript utility library delivering modularity, performance & extras. It provides utility functions for common programming tasks using a functional programming paradigm with over 290 utility functions.
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## Package Information
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- **Package Name**: lodash
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- **Package Type**: npm
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- **Language**: JavaScript
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- **Installation**: `npm install lodash`
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## Core Imports
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```javascript
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// Full library import
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const _ = require('lodash');
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// Individual function imports
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const { map, filter, reduce } = require('lodash');
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```
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ES6 modules:
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```javascript
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// Full library import
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import _ from 'lodash';
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// Individual function imports  
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import { map, filter, reduce } from 'lodash';
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// Method categories
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import * as array from 'lodash/array';
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import * as object from 'lodash/object';
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```
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## Basic Usage
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```javascript
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const _ = require('lodash');
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// Array operations
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const numbers = [1, 2, 3, 4, 5];
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const doubled = _.map(numbers, n => n * 2);
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// => [2, 4, 6, 8, 10]
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// Object manipulation
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const users = [
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  { user: 'barney', age: 36, active: true },
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  { user: 'fred', age: 40, active: false }
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];
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const activeUsers = _.filter(users, { active: true });
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// => [{ user: 'barney', age: 36, active: true }]
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// Function utilities
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const greet = _.template('Hello <%= name %>!');
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const greeting = greet({ name: 'World' });
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// => 'Hello World!'
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// Chaining
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const result = _(users)
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  .filter({ active: true })
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  .map('user')
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  .value();
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// => ['barney']
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```
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## Architecture
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Lodash is organized around several key design principles:
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- **Functional Programming**: Pure functions without side effects where possible
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- **Immutability**: Functions generally don't mutate input data (with exceptions like `_.assign`)
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- **Chainable Interface**: Fluent API allowing method chaining with `_()` wrapper
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- **Modular Design**: Functions can be imported individually to reduce bundle size
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- **Performance Optimized**: Highly optimized implementations with internal caching
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- **Cross-Platform**: Works in browsers, Node.js, and other JavaScript environments
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## Capabilities
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### Array Functions
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Utilities for manipulating arrays including iteration, filtering, transformation, and set operations.
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```javascript { .api }
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// Key array functions
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function chunk(array, size);
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function compact(array);
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function concat(array, ...values);
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function difference(array, ...values);
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function drop(array, n);
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function fill(array, value, start, end);
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function filter(collection, predicate);
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function find(collection, predicate, fromIndex);
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function findIndex(array, predicate, fromIndex);
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function first(array); // alias: head
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function flatten(array);
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function flattenDeep(array);
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function indexOf(array, value, fromIndex);
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function initial(array);
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function intersection(...arrays);
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function join(array, separator);
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function last(array);
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function map(collection, iteratee);
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function pull(array, ...values);
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function pullAll(array, values);
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function remove(array, predicate);
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function reverse(array);
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function slice(array, start, end);
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function sortBy(collection, iteratees);
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function tail(array);
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function take(array, n);
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function union(...arrays);
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function uniq(array);
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function without(array, ...values);
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function zip(...arrays);
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```
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[Array Functions](./array.md)
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### Object Functions
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Utilities for working with objects including property access, manipulation, and transformation.
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```javascript { .api }
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// Key object functions
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function assign(object, ...sources);
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function assignIn(object, ...sources); // alias: extend
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function at(object, paths);
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function create(object, properties);
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function defaults(object, ...sources);
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function findKey(object, predicate);
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function forIn(object, iteratee);
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function forOwn(object, iteratee);
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function functions(object);
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function get(object, path, defaultValue);
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function has(object, path);
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function hasIn(object, path);
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function invert(object);
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function invoke(object, path, ...args);
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function keys(object);
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function mapKeys(object, iteratee);
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function mapValues(object, iteratee);  
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function merge(object, ...sources);
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function omit(object, paths);
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function pick(object, paths);
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function result(object, path, defaultValue);
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function set(object, path, value);
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function transform(object, iteratee, accumulator);
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function unset(object, path);
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function values(object);
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```
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[Object Functions](./object.md)
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### Collection Functions
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Utilities for working with arrays and objects as collections, including iteration, searching, and grouping.
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```javascript { .api }
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// Key collection functions  
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function countBy(collection, iteratee);
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function each(collection, iteratee); // alias: forEach
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function every(collection, predicate);
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function groupBy(collection, iteratee);
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function includes(collection, value, fromIndex);
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function invokeMap(collection, path, ...args);
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function keyBy(collection, iteratee);
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function orderBy(collection, iteratees, orders);
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function partition(collection, predicate);
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function reduce(collection, iteratee, accumulator);
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function reduceRight(collection, iteratee, accumulator);
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function reject(collection, predicate);
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function sample(collection);
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function sampleSize(collection, n);
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function shuffle(collection);
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function size(collection);
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function some(collection, predicate);
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function sortBy(collection, iteratees);
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```
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[Collection Functions](./collection.md)
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### Function Functions
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Utilities for function composition, currying, throttling, and other functional programming patterns.
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```javascript { .api }
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// Key function utilities
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function after(n, func);
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function ary(func, n);
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function before(n, func);
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function bind(func, thisArg, ...partials);
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function bindKey(object, key, ...partials);
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function curry(func, arity);
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function curryRight(func, arity);
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function debounce(func, wait, options);
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function defer(func, ...args);
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function delay(func, wait, ...args);
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function flip(func);
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function memoize(func, resolver);
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function negate(predicate);
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function once(func);
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function partial(func, ...partials);
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function partialRight(func, ...partials);
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function rearg(func, indexes);
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function rest(func, start);
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function spread(func, start);
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function throttle(func, wait, options);
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function unary(func);
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function wrap(value, wrapper);
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```
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[Function Functions](./function.md)
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### String Functions
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Utilities for string manipulation including case conversion, padding, templating, and parsing.
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```javascript { .api }
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// Key string functions
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function camelCase(string);
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function capitalize(string);
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function deburr(string);
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function endsWith(string, target, position);
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function escape(string);
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function escapeRegExp(string);
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function kebabCase(string);
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function lowerCase(string);
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function lowerFirst(string);
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function pad(string, length, chars);
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function padEnd(string, length, chars);
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function padStart(string, length, chars);
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function parseInt(string, radix);
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function repeat(string, n);
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function replace(string, pattern, replacement);
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function snakeCase(string);
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function split(string, separator, limit);
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function startCase(string);
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function startsWith(string, target, position);
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function template(string, options);
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function toLower(string);
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function toUpper(string);
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function trim(string, chars);
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function trimEnd(string, chars);
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function trimStart(string, chars);
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function truncate(string, options);
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function unescape(string);
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function upperCase(string);
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function upperFirst(string);
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function words(string, pattern);
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```
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[String Functions](./string.md)
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### Number Functions
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Utilities for mathematical operations, number validation, and formatting.
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```javascript { .api }
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// Key number functions
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function add(augend, addend);
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function ceil(number, precision);
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function clamp(number, lower, upper);
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function divide(dividend, divisor);
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function floor(number, precision);
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function inRange(number, start, end);
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function max(array);
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function maxBy(array, iteratee);
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function mean(array);
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function min(array);
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function minBy(array, iteratee);
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function multiply(multiplier, multiplicand);
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function random(lower, upper, floating);
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function round(number, precision);
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function subtract(minuend, subtrahend);
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function sum(array);
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function sumBy(array, iteratee);
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```
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[Number Functions](./number.md)
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### Type Checking Functions
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Utilities for runtime type checking and validation.
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```javascript { .api }
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// Key type checking functions
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function isArguments(value);
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function isArray(value);
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function isArrayLike(value);
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function isArrayLikeObject(value);
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function isBoolean(value);
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function isDate(value);
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function isElement(value);
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function isEmpty(value);
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function isEqual(value, other);
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function isEqualWith(value, other, customizer);
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function isError(value);
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function isFinite(value);
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function isFunction(value);
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function isInteger(value);
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function isLength(value);
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function isMatch(object, source);
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function isMatchWith(object, source, customizer);
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function isNaN(value);
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function isNative(value);
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function isNil(value);
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function isNull(value);
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function isNumber(value);
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function isObject(value);
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function isObjectLike(value);
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function isPlainObject(value);
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function isRegExp(value);
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function isSafeInteger(value);
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function isString(value);
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function isSymbol(value);
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function isTypedArray(value);
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function isUndefined(value);
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```
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[Type Functions](./type.md)
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### Utility Functions
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General utility functions including templating, identity, uniqueId generation, and more.
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```javascript { .api }
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// Key utility functions
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function attempt(func, ...args);
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function cond(pairs);
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function conforms(source);
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function constant(value);
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function flow(...funcs);
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function flowRight(...funcs);
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function identity(value);
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function iteratee(func);
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function matches(source);
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function matchesProperty(path, srcValue);
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function method(path, ...args);
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function methodOf(object, ...args);
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function mixin(object, source, options);
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function noConflict();
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function noop();
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function nthArg(n);
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function over(...iteratees);
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function overArgs(func, ...transforms);
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function overEvery(...predicates);
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function overSome(...predicates);
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function property(path);
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function propertyOf(object);
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function range(start, end, step);
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function rangeRight(start, end, step);
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function runInContext(context);
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function stubArray();
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function stubFalse();
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function stubObject();
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function stubString();
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function stubTrue();
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function times(n, iteratee);
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function toPath(value);
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function uniqueId(prefix);
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```
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[Utility Functions](./utility.md)
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## Types
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```javascript { .api }
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// Lodash wrapper for chaining
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interface LodashWrapper<T> {
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  value(): T;
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  valueOf(): T;
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  commit(): LodashWrapper<T>;
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  next(): { done: boolean, value: T };
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  plant(value: any): LodashWrapper<any>;
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  reverse(): LodashWrapper<T>;
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  toJSON(): T;
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  toString(): string;
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}
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// Template options
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interface TemplateOptions {
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  escape?: RegExp;
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  evaluate?: RegExp;
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  imports?: object;
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  interpolate?: RegExp;
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  sourceURL?: string;
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  variable?: string;
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}
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// Debounce/Throttle options
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interface DebounceSettings {
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  leading?: boolean;
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  maxWait?: number;
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  trailing?: boolean;
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}
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// Truncate options  
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interface TruncateOptions {
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  length?: number;
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  omission?: string;
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  separator?: string | RegExp;
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}
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```