localstoragejs

#LocalStorage A wrapper library for HTML5's native localStorage, with some utility functions, validation and namespacing.

##Installation You can install the library by using bower install localstoragejs or you can checkout the repo directly. Depending on your configuration, either incude the file in the src directory or the one in the dist directory.

The module exposes both a global LocalStorage variable and, if you're using it, a requirejs module.

##Usage You can use the module directly from the LocalStorage global variable through its static methods, that allow for a straightforward wrapping of the localStorage functions. The only difference is that whatever you're saving in the dictionary is automatically stringified/parsed as JSON.

LocalStorage.set('myValue', 15); // Saves the value 15 as `myValue`.
LocalStorage.get('myValue'); // Retrieves whatever is saved in `myValue`.
LocalStorage.remove('myValue'); // Clears the `myValue` key
LocalStorage.clear(); // Removes everything from local storage.

If you want more flexibility, you can create an instance of the LocalStorage object. This will namespace all the keys to the name of the instance, and will also allow you to use validators.

###Namespacing Namespacing allows you to 'group' keys together by using a common prefix, which is based on the string you pass to the LocalStorage constructor.

// Creates an instance of the LocalStorage object. 
// All the keys will be namespaced within "DB"
var db = new LocalStorage('DB'); 

// Saves the array [1,2,3] in the 'myValue' key for the "DB" namespace. 
// This means that the real key will be "DB:myValue".
db.set('myValue', [1,2,3]); 

// Retrieves [1,2,3] from the 'myValue' key within the "DB" namespace. 
// This means that you're retrieving whatever is saved within the "DB:myValue" key.
db.get('myValue'); 

// Removes the 'myValue' key from the DB namespace. 
// You're actually removing the "DB:myValue" key.
db.remove('myValue'); 

// Retrieves all the keys for the current object's namespace. 
// In this instance, you're retrieving all the keys that begin with "DB:"
db.all(); 

// Clears all the keys associated to the object's namespace. 
// Here, you'll be removing all the keys that begin with "DB:"
db.clear(); 

###Validation Sometimes you might want to validate a value before saving it. Validators serve exactly that purpose and come in two flavors: one-shot and permanent.

When you create an instance of the LocalStorage object, you have the option to pass a second parameter with some options. Right now, the only option available is the blockingValidation option which, if set to true, makes the set call throw a LocalStorageException when failing validation instead of simply returning false.

####One-shot validators A one-shot validator is evaluated within the scope of a single set call and is not saved within your LocalStorage object instance.

var db = new LocalStorage('DB');

// This will fail since the passed value does not pass the validation test.
db.set('username', 'fred', function(value) {
	return value.length >= 8;
});

####Permanents validators A permanent validator is associated with a key and will be called anytime you attempt to save a value for that key. A permanent validator has lower priority than a one-shot validator, so you can always override it by passing a one-shot validator (or true) to a set call.

// By passing the 'blockingValidation' option, we make 
// the 'set' call throw an exception when validation fails.
var db = new LocalStorage('DB', {blockingValidation: true});

db.setValidator('username', function(value) {
	return value.length >= 8;
});

// This will fail
db.set('username', 'fred');

// This will pass
db.set('username', 'fred1234');

// This too wil pass
db.set('username', 'fred', function(value) { return value === 'fred'; });

// If you just want to skip validation for a single call, go ahead:
db.set('username', 'brad', true);

If you want to clear a permanent validator, or you want to clear all of them, you can do so by calling either the clearValidator or the clearValidators functions:

// This will clear the permanent validator associated with the 'username' key
db.clearValidator('username');

// This will clear all the permanent validators on this instance of LocalStorage
db.clearValidators();

###Chaining The following instance methods are chainable:

• set (when validation passes)
• remove
• all
• setValidator
• clearValidator
• clearValidators

That's pretty much it (for now)!

##A note on compatibility I'm assuming this library will be used in projects made for modern browsers. I haven't put any effort in testing compatibility other than to check if the localStorage variable is present on the global scope. If you feel that this is not sufficient, please send a PR and I will consider it!

##Promises? Even though all this stuff is synchronous, I'm toying with the idea of using promises instead of/alongside return values. For example, there could be an option like usePromises that makes each method return a promise instead of the result of the operation or the object itself (for chainable methods). This would remove the ambiguity of the return value for the set method, and would allow - with some tweaking - the use of asynchronous validators. For this purpose I would need to make this library dependent on a library such as Q or BlueBird. Thoughts?

##Contributing If you find bugs or things you don't like, please send a PR. Remember to build the minified version of library using grunt and update the README if required.

##License MIT