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.

1. André Faria
@andrefaria
Underscore.js
http://documentcloud.github.com/underscore/

2. 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.

3. 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.

4. It delegates to built-in functions, if present, so
modern browsers will use the native
implementations of forEach, map, reduce, filter,
every, some andindexOf.

7. 2 Versions

8. Object Oriented
and Fuction Styles
your preference

9. Using the object-oriented style allows you to chain
together methods. Calling chain on a wrapped object
will cause all future method calls to return wrapped
objects as well. When you've finished the computation,
use value to retrieve the final value.

11. Collection Functions
(Arrays or Objects)

31. Array Functions
All array functions will also work on the arguments object.

47. Functions

60. Objects

74. Utility

84. Chaining

88. There’s more

90. Thanks very much
and now go try it out
@andrefaria