Lazy.js

Lazy.js it a utility library for JavaScript, similar to Underscore and Lo-Dash but with one important difference: lazy evaluation (also known as deferred execution). This can translate to superior performance in many cases, especially when dealing with large arrays and/or "chaining" together multiple methods. For simple cases (map, filter, etc.) on small arrays, Lazy's performance should be similar to Underscore or Lo-Dash.