A coffeescript wrapper around cookies and localstorage

store.coffee

# store.js
# a simple wrapper around html5 local storage and cookies
# provides three methods to interact with data
#
# it automatically purges data from localStorage if it's full.
#
# set: key, value
#    stores the value in a key
#    returns the value
# get: key
#    retrieves the value in the key
#    returns the value
# expire: key
#    removes the data and the key
#    returns the value

Store = do ->
  localStorageSupported = do ->
    try
      `(('localStorage' in window) && window['localStorage'] !== null)`
    catch e
      false

  if localStorageSupported
    # will displace data until it can successfully save
    safeSet = (key, value) ->
      try
        localStorage.setItem key, value
        value
      catch e
        for num in [0..5]
          localStorage.removeItem localStorage.key localStorage.length - 1
        safeSet key, value
    {
      set: safeSet

      get: (key) ->
        localStorage[key]

      expire: (key) ->
        value = localStorage[key]
        localStorage.removeItem(key)
        value
    }
  else
    createCookie = (name, value, days) ->
      if days
        date = new Date
        date.setTime(date.getTime() + (days*24*60*60*1000))
        expires = "; expires=" + date.toGMTString()
      else
        expires = ""

      document.cookie = name + "=" + value + expires + "; path=/"

      value

    getCookie = (key) ->
      key = key + "="
      for cookieFragment in document.cookie.split(';')
        return cookieFragment.replace(/^\s+/, '').substring(key.length, cookieFragment.length) if cookieFragment.indexOf(key) == 0
      return null

    {
      set: (key, value) ->
        createCookie key, value, 1

      get: getCookie

      expire: (key) ->
        value = Store.get key
        createCookie key, "", -1
        value
    }

store.js

var Store;
Store = (function() {
  var createCookie, getCookie, localStorageSupported, safeSet;
  localStorageSupported = (function() {
    try {
      return (('localStorage' in window) && window['localStorage'] !== null);
    } catch (e) {
      return false;
    }
  })();
  if (localStorageSupported) {
    safeSet = function(key, value) {
      var num;
      try {
        localStorage.setItem(key, value);
        return value;
      } catch (e) {
        for (num = 0; num <= 5; num++) {
          localStorage.removeItem(localStorage.key(localStorage.length - 1));
        }
        return safeSet(key, value);
      }
    };
    return {
      set: safeSet,
      get: function(key) {
        return localStorage[key];
      },
      expire: function(key) {
        var value;
        value = localStorage[key];
        localStorage.removeItem(key);
        return value;
      }
    };
  } else {
    createCookie = function(name, value, days) {
      var date, expires;
      if (days) {
        date = new Date;
        date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
        expires = "; expires=" + date.toGMTString();
      } else {
        expires = "";
      }
      document.cookie = name + "=" + value + expires + "; path=/";
      return value;
    };
    getCookie = function(key) {
      var cookieFragment, _i, _len, _ref;
      key = key + "=";
      _ref = document.cookie.split(';');
      for (_i = 0, _len = _ref.length; _i < _len; _i++) {
        cookieFragment = _ref[_i];
        if (cookieFragment.indexOf(key) === 0) {
          return cookieFragment.replace(/^\s+/, '').substring(key.length, cookieFragment.length);
        }
      }
      return null;
    };
    return {
      set: function(key, value) {
        return createCookie(key, value, 1);
      },
      get: getCookie,
      expire: function(key) {
        var value;
        value = Store.get(key);
        createCookie(key, "", -1);
        return value;
      }
    };
  }
})();

Right now getCookie() hangs Firefox.

Some corrections

On line #27 and #28, instead of

  cookieFragment: cookieFragment.substring(1, cookieFragment.length) 
return cookieFragment.substring(key.length, cookieFragment.length) if cookieFragment.indexOf(key) == 0

it should be

  cookieFragment = cookieFragment.substring(1, cookieFragment.length) 
return cookieFragment.substring(key.length+1, cookieFragment.length) if cookieFragment.indexOf(key) == 0

@nasa42 try https://github.com/deleteme/store

Line 27 should be
set: (key, value) -> localStorage[key]: value