CoffeeScript QueryString class

querystring.coffee

# Provide easy access to QueryString data
class QueryString
	
	constructor: (@queryString) ->
		@queryString or= window.document.location.search?.substr 1
		@variables = @queryString.split '&'
		@pairs = ([key, value] = pair.split '=' for pair in @variables)
	
	get: (name) ->
		for [key, value] in @pairs
			return value if key is name

Pros/cons of caching in the constructor. I'm a big fan of only doing work if its needed so I would lazy load the hash when first accessed via the get method (as you might include this code in a library but not actually use it?). But if you know you will be using it then by all means do it in the constructor. QS is never going to be that big so this should be blazingly fast anyway. As usual don't get too hung up on optimising, some stuff I just do "as the norm" but its rare you need to go much beyond getting it just working, just me being picky :)

All you need to do to address decoding is run both key and value through decodeURIComponent.