Underscore is a
utility-belt library for JavaScript that provides a lot of the
functional programming support that you would expect in
Prototype.js
(or Ruby),
but without extending any of the built-in JavaScript objects. It's the
tie to go along with jQuery's tux.
Underscore provides 60-odd functions that support both the usual
functional suspects: map, select, invoke —
as well as more specialized helpers: function binding, javascript
templating, deep equality testing, and so on. It delegates to built-in
functions, if present, so modern browsers will use the
native implementations of forEach, map, reduce,
filter, every, some and indexOf.
