WebApps with LocalStorage and AppCache/Remote Data Download

For an AppLSAC-0 it is allowed to download data from a remote server.

Learning Objective
In this part you will learn, how AppLSACs can be able to download data from a remote server.
 * We learn about different digital footprints of WebApps.
 * We learn about the requirements and constraints ofan AppLSAC-0. A remote download operation must be triggered by a users. For an AppLSAC-0 downloads from remote servers are not allowed, if they are "silently" performed by
 * script tags that inject remote libraries from other servers (e.g. CDNs, injection of remotely maintained code into WebApp)
 * fonts by remotely injected CSS,
 * images (remotely injected images by img tags),
 * iframes with remote content,

Remark: It should be clarified that Content Delivery Networks IT services deliver an IT service to customers. Companies that provide CDN services must cover the server and traffic costs by fees or offering user analytics of the digital footprint of users and devices. A remote code injection by a CDN does not mean that illegal parts of the library are injected into your WebApp. CDN provide in general a compressed code of a library, that performs the job as expected from the library on Git repository. There is nothing wrong with using CDNs. AppLSAC-0 define just requirements, to minimized the digital footprint of WebApps and therefore libraries are loaded from the webserver of the AppLSAC or stored locally on your computer or mobile device. The learning resource about AppLSACs focuses on basic programming techniques and the consequence for the digital footprint and how software design and library management could reduce the digital footprint (see also Commercial Data Harvesting). CDNs and remote library injection is just one example for digital footprints of WebApps.