MICROSOFT_PRESS_EBOOK_PROGRAMMING_WINDOWS_8_APPS_WITH_HTML_CSS_AND_JAVASCRIPT_PDF

Sidebar: WinJS.Namespace.define and WinJS.Class.define
WinJS.Namespace.define provides a shortcut for the JavaScript namespace pattern. This helps to
minimize pollution of the global namespace as each app-defined namespace is just a single
object in the global namespace but can provide access to any number of other objects, functions,
and so on. This is used extensively in WinJS and is recommended for apps as well, where you
define everything you need in a module—that is, within a (function() { ... })() block—and
then export selective variables or functions through a namespace. In short, use a namespace
anytime you’re tempted to add any global objects or functions!
The syntax: var ns = WinJS.Namespace.define(, ) where is a string
(dots are OK) and is any object contained in { }’s. Also, WinJS.Namespace.-
defineWithParent(, , ) defines one within the namespace.
If you call WinJS.Namespace.define for the same multiple times, the are
combined. Where collisions are concerned, the most recently added members win. For example:
WinJS.Namespace.define("MyNamespace", { x: 10, y: 10 });
WinJS.Namespace.define("MyNamespace", { x: 20, z: 10 });
//MyNamespace == { x: 20, y: 10, z: 10}
WinJS.Class.define is, for its part, a shortcut for the object pattern, defining a constructor so
that objects can be instantiated with new.
Syntax: var className = WinJS.Class.define(, ,
) where is a function, is an object with the
class’s properties and methods, and is an object with properties and methods
that can be directly accessed via . (without using new).
Variants: WinJS.Class.derive(, ...) creates a subclass (... is the same arg list as
with define) using prototypal inheritance, and WinJS.Class.mix(, [])
defines a class that combines the instance (and static) members of one or more other
and initializes the object with .
Finally, note that because class definitions just generate an object, WinJS.Class.define is
typically used inside a module with the resulting object exported to the rest of the app as a
namespace member. Then you can use new . anywhere in the app.
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