Complete toolkit for Lodash 4.18 utility library providing 300+ helper functions for arrays, collections, objects, strings, numbers, dates, and functions. Use when building JavaScript applications requiring robust data manipulation, functional programming patterns, type checking, or cross-platform compatibility without native ES6+ features.
Complete toolkit for Lodash 4.18 utility library providing 300+ helper functions for arrays, collections, objects, strings, numbers, dates, and functions. Use when building JavaScript applications requiring robust data manipulation, functional programming patterns, type checking, or cross-platform compatibility without native ES6+ features.
Lodash 4.18
Overview
Lodash is a JavaScript utility library delivering consistency, modularity, performance, and extras. It provides over 300 helper functions organized into 11 categories: Array, Collection, Date, Function, Lang, Math, Number, Object, Seq, String, and Util. Lodash makes JavaScript easier by taking the hassle out of working with arrays, numbers, objects, strings, and more.
The library is released under the MIT license and supports modern environments including Node.js 4+, Bun 1.0+, and the latest Chromium, Firefox, WebKit, and Edge browsers with best-effort support for Chrome 74+, Firefox 66+, IE 11, Edge 18, and Safari 11+.
When to Use
Iterating arrays, objects, and strings with consistent cross-browser behavior
Manipulating and testing values (type checking, deep equality, cloning)
Matches shorthand — passes a source object to create a function that performs a partial deep comparison:
_.filter(users, { 'active': true, 'role': 'admin' });
// Returns users where both active === true AND role === 'admin'
MatchesProperty shorthand — passes a [key, srcValue] pair to create a function that checks if an element's property matches the source value:
_.find(users, ['active', false]);
// Finds first user where user.active === false
Lazy Evaluation
Lodash chains support lazy evaluation — when possible, method calls are compiled into a single optimized function. This avoids creating intermediate arrays and dramatically improves performance on large collections:
// Without chaining — creates multiple intermediate arrays
_.map(_.filter(largeArray, predicate), transform);
// With chaining — single pass, lazy evaluation_(largeArray).filter(predicate).map(transform).value();
