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File in Windows Store Apps

By Deepak Middha on Nov 01, 2012
In this app I described how store data in a file in roaming folder in a Windows Store App using JavaScript.


In this article I describe how to create a Windows Store App for storing data in a file in roaming folder using JavaScript. User data in an app can be stored as files. There are three locations available for storing files; they are:

  1. Windows.Storage.ApplicationData.current.localFolder
  2. Windows.Storage.ApplicationData.current.roamingFolder
  3. Windows.Storage.ApplicationData.current.temporaryFolder.
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 one JavaScript page by right-clicking on the js folder in the Solution Explorer and select Add > new item > JavaScript Page and then give an appropriate name. In the same way, add one HTML page to your project.


Write the following code in default.html:

<!DOCTYPE html>



    <meta charset="utf-8" />


    <link rel="stylesheet" href="//Microsoft.WinJS.1.0/css/ui-light.css" />

    <script src="//Microsoft.WinJS.1.0/js/base.js"></script>

    <script src="//Microsoft.WinJS.1.0/js/ui.js"></script>

    <link rel="stylesheet" href="/css/default.css" />

    <script src="/js/default.js"></script>


<body role="application" style="background-color: lightyellow">

    <center><div id="rootGrid">

         <div id="content">

            <h1 id="featureLabel"></h1>

            <div id="contentHost"></div>





Write the following code in default.js:

(function () {

    "use strict";

    var appTitle = "";

    var pages = [

        { url: "page.html", title: "SetVersion" }


    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();


        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);



Write the following code in page.html:





    <link rel="stylesheet" href="/css/default.css" />

    <script src="/js/script.js"></script>



    <div data-win-control="App.pageInput">

        <button class="action" id="filesIncrement">Create File</button>


    <div data-win-control="App.pageOutput">

        <div class="item" id="filesOutput"></div>




Write the following code in script.html:

function () {

    "use strict";

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

        ready: function (element, options) {

            document.getElementById("filesIncrement").addEventListener("click", filesIncrement, false);




    var roamingFolder = Windows.Storage.ApplicationData.current.roamingFolder;

    var filename = "appFile.txt";

    var counter = 0;

    function filesIncrement() {

        counter = counter + 1;


        roamingFolder.createFileAsync(filename, Windows.Storage.CreationCollisionOption.replaceExisting)

            .then(function (file) {

                return Windows.Storage.FileIO.writeTextAsync(file, counter);

            }).done(function () {




    function filesReadCounter() {


            .then(function (file) {

                return Windows.Storage.FileIO.readTextAsync(file);

            }).done(function (text) {

                counter = parseInt(text);

                document.getElementById("filesOutput").innerText = "file: " + counter;

            }, function () {

                document.getElementById("filesOutput").innerText = "file: <not found>";



    function filesDisplayOutput() {







In this app I described how to store data in a file in a roaming folder 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.

Deepak Middha
Deepak Middha

Deepak Middha is one time Microsoft MVP(Client App Dev) , working as Sr. Software Developer with lots of hands on experience using ASP.NET 2.0/3.5, AJAX, MVC, C#,  SQL Server 2005/2008/2012, WCF, JQuery and Silverl... Read more