WinJS variable is changed only inside function

Question

I have a problem with variable scope in WinJS. When the variable is changed it should be visible in bigger scope, but after call function this variable has value only inside function. I think it is problem with readTextAsync, because when I fill variable in function without readTextAsync, it is working.

This is variable declaration:

var fileDate;

This is function where I call another:

WinJS.UI.Pages.define("index.html", {
        ready: function (element, options) {
            loadDate();
            console.log("główna " + fileDate); //fileDate = undefined
            this.fillYearSelect();
        },

And this is function, where variable is changed:

localFolder.getFileAsync(filename).then(function (file) {
              Windows.Storage.FileIO.readTextAsync(file).done(function (fileContent) {
                 fileDate = fileContent; // example - fileDate=a073z160415
                 console.log("fileDate " + fileDate);
            },
            function (error) {
                console.log("Reading error");
            });
        },
        function (error) {
            console.log("File not found");
        });
    }

P.S. Sorry for my English. It isn't perfect :)

Answer 1

I think it is problem with readTextAsync, because when I fill variable in function without readTextAsync, it is working.

I made this answer from your last post's codes.Windows.Storage.FileIO.readTextAsync is a windows async api. So it should be handled in async way: console.log("główna " + fileDate) should be handled in loadDate().then() like below and fileContent should be returned,and you can catch it in loadDate().then(function(data){}).

WinJS.UI.Pages.define("index.html", {
    ready: function (element, options) {
        loadDate().then(function(data){
           fileDate=data;   //here catch the fileContent data
           console.log("główna " + fileDate); 
        });
        this.fillYearSelect();
    },

function loadDate() {
            var that = this;
            var filename = "abc.txt";
            return Windows.Storage.ApplicationData.current.localFolder.getFileAsync(filename).then(function (file) {
                return Windows.Storage.FileIO.readTextAsync(file).then(function (fileContent) {
                    return fileContent;//here return the fileContent.You can catch it outside.
                },
                function (error) {
                    console.log("Błąd odczytu");
                });
            },
            function (error) {
                console.log("Nie znaleziono pliku");
            });
        }