Angular 2 - Data persistence
While building client-side apps, your
intent is typically to work with some kind of data in a read-write
fashion. So you end up needing a way to pull and process data from
Javascript in the client. This is handled in a couple of different
ways with Angular, depending on the source of your data.
If you are only concerned with storing
data for the time in which the user is using your application, you
could store that data in memory.
Angular's dependency injection makes this
fairly trivial to do. You can create a Javascript class or object to
store your data, provide it to your app as something that can be injected
in, and then do constructor injection where needed to bring in the
instance of that object. From there, you can do read-write updates to
that object and have the changes available throughout.
To work with data stored in browser
storage, such as local storage, you will find the need to write your
own Javascript code to do so, and then use it with the services pattern,
leveraging Angular's dependency injection to work with it throughout
your application. If you are looking to work with data from the
server via an API, Angular has some built in framework stuff to help
you with that. One way you can process data to and from an API is by
leveraging the HTTP protocol. You can do this in two ways.
One, by using the XML HTTP request or
XHR and the other by using JSONP.
Angular provides an HTTP module in the
framework for abstracting out working with the way XHR and
JSONP calls are done via client script. So you can do things like
make GET and POST calls that work with JSON data as simple as
passing a URL and a Javascript object to an Angular HTTP function and
subscribing to the results.
