Defining a Simple Object in Windows Store Apps

Introduction

In this article I describe how to create a Windows Store App using JavaScript that defines an Object. The sample app demonstates definition of a simple JavaScript object, with methods and defaults being placed on the function prototype, using the Win.Class.define method.

I assume you can create a simple Windows Store App using JavaScript. For more help visit Simple Windows Store Apps using JavaScript.

To start the creation of the app, add two JavaScript pages by right-clicking on the js folder in the Solution Explorer and select Add > new item > JavaScript Page and then provide an appropriate name. In the same way, add one HTML page to your project.

Write the following code in default.html:

<!DOCTYPE html>

<html>

<head>

</head>

</div>

</center>

</body>

</html>

Write the following code in default.js:

(function () {
"use strict";

var appTitle = "";

var pages = [

{ url: "page.html" }

];

function activated(eventObject) {

if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) {

eventObject.setPromise(WinJS.UI.processAll().then(function () {

var url = WinJS.Application.sessionState.lastUrl || pages[0].url;

return WinJS.Navigation.navigate(url);

}));

}

WinJS.Navigation.addEventListener("navigated", function (eventObject) {

var url = eventObject.detail.location;

var host = document.getElementById("contentHost");

host.winControl && host.winControl.unload && host.winControl.unload();

WinJS.Utilities.empty(host);

eventObject.detail.setPromise(WinJS.UI.Pages.render(url, host, eventObject.detail.state).then(function () {

WinJS.Application.sessionState.lastUrl = url;

}));

});

WinJS.Namespace.define("app", {

appTitle: appTitle,

pages: pages

});

WinJS.Application.addEventListener("activated", activated, false);

WinJS.Application.start();

})();

Write the following code in page.html:

<!DOCTYPE html>

<html>

<head>

</head>

<body>

<button class="action winClassDefineCreateInstance">Create Instance of Defined Class</button>

<button class="action secondary winClassDefineCreateAndSetProperties">Create Instance and set properties</button>

<br />

</div>

<table>

<thead>

<tr>

<th>Member</th>

<th>Value</th>

<th>From Prototype?</th>

</tr>

</thead>

<tbody>

</tr>

</tr>

<td>Width</td>

</tr>

<td>Height</td>

</tr>

</tr>

<td>ToString</td>

</tr>

</tbody>

</table>

</div>

</body>

</html>

Write the following code in script.js:

(function () {

"use strict";

var Rect = WinJS.Class.define(

function () { },

{

x: 0,

y: 0,

width: 0,

height: 0,

area: function () { return this.width * this.height; },

toString: function () {

return "rectangle (" +

[this.x, this.y, this.width, this.height].join(", ") +

")";

}

);

function defaultRect() {

WinJS.log && WinJS.log("Default state of new Rect object", "app", "status");

return new Rect();

}

function rectWithPropertyChanges() {

WinJS.log && WinJS.log("Status of rect after properties get set", "app", "status");

var r = new Rect();

r.width = 5;

r.height = 4;

return r;

}

var page = WinJS.UI.Pages.define("page.html", {

ready: function (element, options) {

var root = new WinJS.Utilities.QueryCollection(element);

this.outputTable = root.query(".winClassDefineOutputTable");

this.hideOutputTable();

root.query(".winClassDefineCreateInstance").listen("click", this.showDefaultRect.bind(this));

root.query(".winClassDefineCreateAndSetProperties").listen("click", this.showRectWithPropertyChanges.bind(this));

hideOutputTable: function () {

this.outputTable.setStyle("visibility", "hidden");

showOutputTable: function () {

this.outputTable.setStyle("visibility", "visible");

showDefaultRect: function () {

this.showOutputTable();

this.displayRect(defaultRect());

showRectWithPropertyChanges: function () {

this.showOutputTable();

this.displayRect(rectWithPropertyChanges());

displayRect: function (rect) {

this.updateRow("X", rect.x, rect.hasOwnProperty("x"));

this.updateRow("Y", rect.y, rect.hasOwnProperty("y"));

this.updateRow("Width", rect.width, rect.hasOwnProperty("width"));

this.updateRow("Height", rect.height, rect.hasOwnProperty("height"));

this.updateRow("Area", rect.area(), rect.hasOwnProperty("area"));

this.updateRow("ToString", rect.toString(), rect.hasOwnProperty("toString"));

updateRow: function (rowIdSuffix, propertyValue, isOwnProperty) {

var tr = this.outputTable.query(".winClassDefine" + rowIdSuffix)[0];

tr.cells[1].innerText = propertyValue;

tr.cells[2].innerText = isOwnProperty ? "no" : "yes";

}

});

})();

Output:

Summary

In this app I described how to define a simple Object in a Windows Store App using JavaScript. I hope this article has helped you to understand this topic. Please share if you know more about this. Your feedback and constructive contributions are welcome.

Defining a Simple Object in Windows Store Apps

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