Underscore.js

Moohanad HassanMaedeh Pishvae

OOP vs. Functional Programming?

OOP• Fixed set of operation on things•  As your code evolves, you add new things (like a

class)FP

•  Fixed set of things• As your code evolves, you add new operations  (like a

function) on existing things

Functional Programming

JavaScript• Uses functions to turns one value into

another 

• Taking a value, and returns a new value with no “side effect”

• Side effect: internal changes doesn’t affect outside of function

What is Underscore?

Underscore is a utility-belt library for JavaScript that provides a lot of the

functional programming support that you would expect in Ruby, but without extending any of the built-in JavaScript

objects.

JQuery

• jQuery does DOM (Document Object Model) manipulation and animation extremely well.

• DOM: Virtual map of webpage loaded on browser

• Most of jQuery  functionality deals with the DOM, so it has little purpose outside the browser

jQuery and Underscore go hand in hand

• jQuery doesn’t deal with anything in the higher or lower levels

• For higher level: Backbone or Knockout

• For lower level: Underscore

Underscore Complements jQuery

• Complements jQuery by its functional support– Collections– Arrays– Functions– Objects– Utilities

http://aveic.ru/underscorejs/cheatsheet.pdf

Features

• No other dependencies

• Adds very little overhead to your total script

• Can be used on the client or server 

• Good for MVC or non-DOM code

• Doesn’t modify built-in objects

Underscore Is Flexible

• Functional or Object-Oriented Style

• Chainable– Chain method tells Underscore to

return wrapped object– Value method returns the final at the

end

RESOURCESDocumentation:http://documentcloud.github.com

Good Libraries Reduce the Burden

Examples