Windows 8 Programming with HTML and JavaScript

Chad McCallumASP.NET/IIS MVP

iQmetrix Softwarehttp://www.rtigger.com

@ChadEmm / chadm@iqmetrix.com

Windows RT API

Windows Runtime is implemented at a low-level and then “projected” into C++, C#, VB, and JavaScript APIs

Allows the APIs to present the same functionality in a way that’s familiar to developers of that language

Native App in HTML?

Apps are run in an Internet Explorer 10 shell

This means:Can include other JS librariesHTML5 and CSS3 support for user interfaceCan do (almost) anything you’d do with a web

application

What are these apps called?

Windows Store appsAcquired, installed, and updated via the

Windows Store appPackaged into an “.appx” file when submittedContains a manifest file that describes the app,

the resources it uses (camera, network, etc.), and lists OS integrations (background tasks, file associations, etc.)

Windows Library for JavaScriptaka WinJSWrapper for Windows Runtime APIProvides:

Access to system-level resourcesHTML implementation of WinRT controls,

complete with CSS styling and eventsCSS3-based animation frameworkHelpers for common coding patterns

Not Quite a Web Page

Some DOM API calls are modified or unavailable, like alert or window.open

There are some methods, properties, and CSS queries that are specific to a Windows Store app

Allowed to make cross-domain requests, load resources from remote sources

Not Quite a Web Page

Not allowed to reference scripts remotely

IFrames are run in “web context” without access to WinRT

Some DOM-based calls are modified or removed (document.write, innerHTML)

App Container

Run within a dedicated environment that can’t access other applications and the system directly

Have unrestricted read/write access to their own appdata folders

Access to any other files or hardware goes through a broker, which can deny access

App Lifecycle4-ish states

Starting: shows splash screen image, does all the app initialization behind the scenes

Running: active application on user’s device Suspending: app has lost focus, 5 seconds to save

state Resuming: app has regained focus

Suspended: still in memory, but not allocated any CPU time

Terminated: removed from memory, effectively closed. OS triggers this at will, app is not informed

App StateWhen being “suspended”, Windows 8 gives your

app approximately 5 seconds to save its state

Can save data as Temp, Local, and RoamingSave as a file and/or key-value pairsAlways app-specific, as they’re saved relative to

your app’s directoryRoaming settings are uploaded to user’s Microsoft

Account and are accessible across devices

Code Time!