store/store.js

;(function(win){
	var store = {},
		doc = win.document,
		localStorageName = 'localStorage',
		scriptTag = 'script',
		storage

	store.disabled = false
	store.set = function(key, value) {}
	store.get = function(key) {}
	store.remove = function(key) {}
	store.clear = function() {}
	store.transact = function(key, defaultVal, transactionFn) {
		var val = store.get(key)
		if (transactionFn == null) {
			transactionFn = defaultVal
			defaultVal = null
		}
		if (typeof val == 'undefined') { val = defaultVal || {} }
		transactionFn(val)
		store.set(key, val)
	}
	store.getAll = function() {}
	store.forEach = function() {}

	store.serialize = function(value) {
		return JSON.stringify(value)
	}
	store.deserialize = function(value) {
		if (typeof value != 'string') { return undefined }
		try { return JSON.parse(value) }
		catch(e) { return value || undefined }
	}

	// Functions to encapsulate questionable FireFox 3.6.13 behavior
	// when about.config::dom.storage.enabled === false
	// See https://github.com/marcuswestin/store.js/issues#issue/13
	function isLocalStorageNameSupported() {
		try { return (localStorageName in win && win[localStorageName]) }
		catch(err) { return false }
	}

	if (isLocalStorageNameSupported()) {
		storage = win[localStorageName]
		store.set = function(key, val) {
			if (val === undefined) { return store.remove(key) }
			storage.setItem(key, store.serialize(val))
			return val
		}
		store.get = function(key) { return store.deserialize(storage.getItem(key)) }
		store.remove = function(key) { storage.removeItem(key) }
		store.clear = function() { storage.clear() }
		store.getAll = function() {
			var ret = {}
			store.forEach(function(key, val) {
				ret[key] = val
			})
			return ret
		}
		store.forEach = function(callback) {
			for (var i=0; i<storage.length; i++) {
				var key = storage.key(i)
				callback(key, store.get(key))
			}
		}
	} else if (doc.documentElement.addBehavior) {
		var storageOwner,
			storageContainer
		// Since #userData storage applies only to specific paths, we need to
		// somehow link our data to a specific path.  We choose /favicon.ico
		// as a pretty safe option, since all browsers already make a request to
		// this URL anyway and being a 404 will not hurt us here.  We wrap an
		// iframe pointing to the favicon in an ActiveXObject(htmlfile) object
		// (see: http://msdn.microsoft.com/en-us/library/aa752574(v=VS.85).aspx)
		// since the iframe access rules appear to allow direct access and
		// manipulation of the document element, even for a 404 page.  This
		// document can be used instead of the current document (which would
		// have been limited to the current path) to perform #userData storage.
		try {
			storageContainer = new ActiveXObject('htmlfile')
			storageContainer.open()
			storageContainer.write('<'+scriptTag+'>document.w=window</'+scriptTag+'><iframe src="/favicon.ico"></iframe>')
			storageContainer.close()
			storageOwner = storageContainer.w.frames[0].document
			storage = storageOwner.createElement('div')
		} catch(e) {
			// somehow ActiveXObject instantiation failed (perhaps some special
			// security settings or otherwse), fall back to per-path storage
			storage = doc.createElement('div')
			storageOwner = doc.body
		}
		function withIEStorage(storeFunction) {
			return function() {
				var args = Array.prototype.slice.call(arguments, 0)
				args.unshift(storage)
				// See http://msdn.microsoft.com/en-us/library/ms531081(v=VS.85).aspx
				// and http://msdn.microsoft.com/en-us/library/ms531424(v=VS.85).aspx
				storageOwner.appendChild(storage)
				storage.addBehavior('#default#userData')
				storage.load(localStorageName)
				var result = storeFunction.apply(store, args)
				storageOwner.removeChild(storage)
				return result
			}
		}

		// In IE7, keys cannot start with a digit or contain certain chars.
		// See https://github.com/marcuswestin/store.js/issues/40
		// See https://github.com/marcuswestin/store.js/issues/83
		var forbiddenCharsRegex = new RegExp("[!\"#$%&'()*+,/\\\\:;<=>?@[\\]^`{|}~]", "g")
		function ieKeyFix(key) {
			return key.replace(/^d/, '___$&').replace(forbiddenCharsRegex, '___')
		}
		store.set = withIEStorage(function(storage, key, val) {
			key = ieKeyFix(key)
			if (val === undefined) { return store.remove(key) }
			storage.setAttribute(key, store.serialize(val))
			storage.save(localStorageName)
			return val
		})
		store.get = withIEStorage(function(storage, key) {
			key = ieKeyFix(key)
			return store.deserialize(storage.getAttribute(key))
		})
		store.remove = withIEStorage(function(storage, key) {
			key = ieKeyFix(key)
			storage.removeAttribute(key)
			storage.save(localStorageName)
		})
		store.clear = withIEStorage(function(storage) {
			var attributes = storage.XMLDocument.documentElement.attributes
			storage.load(localStorageName)
			for (var i=0, attr; attr=attributes[i]; i++) {
				storage.removeAttribute(attr.name)
			}
			storage.save(localStorageName)
		})
		store.getAll = function(storage) {
			var ret = {}
			store.forEach(function(key, val) {
				ret[key] = val
			})
			return ret
		}
		store.forEach = withIEStorage(function(storage, callback) {
			var attributes = storage.XMLDocument.documentElement.attributes
			for (var i=0, attr; attr=attributes[i]; ++i) {
				callback(attr.name, store.deserialize(storage.getAttribute(attr.name)))
			}
		})
	}

	try {
		var testKey = '__storejs__'
		store.set(testKey, testKey)
		if (store.get(testKey) != testKey) { store.disabled = true }
		store.remove(testKey)
	} catch(e) {
		store.disabled = true
	}
	store.enabled = !store.disabled

	if (typeof module != 'undefined' && module.exports && this.module !== module) { module.exports = store }
	else if (typeof define === 'function' && define.amd) { define(store) }
	else { win.store = store }

})(Function('return this')());