Underscore.js is a lightweight JavaScript library that provides a wide array of functional programming helpers without extending any built-in objects. It's the Swiss Army knife for developers, offering over 100 functions that support both your favorite workaday functional helpers: map, filter, invoke—as well as more specialized goodies: function binding, javascript templating, creating quick indexes, deep equality tests, and so on.
Designed to be a utility belt for JavaScript projects, Underscore makes it easier to work with arrays, objects, and functions. For instance, it can be used to iterate over an array with a simple syntax, manipulate and test objects, and create sophisticated functions with its powerful composition abilities. Its minimalist approach means it doesn't bloat your projects but instead provides a solid foundation of tools for building robust applications.
Underscore can be mixed and used alongside other libraries like jQuery or Backbone.js, offering a functional programming complement to these tools' rich feature sets. Despite the emergence of ES6 and newer JavaScript features that replicate some of its functionalities, Underscore remains popular for its simplicity, efficiency, and compatibility across a wide range of browsers and environments.
