helpers.js

var MyHelpers = {
    extend: function (out) {
        out = out || {};

        for (var i = 1; i < arguments.length; i++) {
            if (!arguments[i]) {
                continue
            }

            for (var key in arguments[i]) {
                if (arguments[i].hasOwnProperty(key)) {
                    out[key] = arguments[i][key]
                }
            }
        }

        return out
    },

    readLocalSetting: function(key) {
        var applicationData = Windows.Storage.ApplicationData.current
          , localSettings   = applicationData.localSettings

        return localSettings.values[key]
    },

    writeLocalSetting: function(key, value) {
        var applicationData = Windows.Storage.ApplicationData.current
          , localSettings   = applicationData.localSettings

        localSettings.values[key] = value
    },

    dropbox: {
        KEY: "0k6lggamswvcpeq",
        SECRET: "chani4pw0g54tqk",

        getParams: function() {
            return JSON.parse(MyHelpers.readLocalSetting('dropboxParams'))
        },

        setParams: function(params) {
            MyHelpers.writeLocalSetting('dropboxParams', JSON.stringify(params))
        },

        getClient: function() {
            var options = MyHelpers.extend({
                key: MyHelpers.dropbox.KEY,
                secret: MyHelpers.dropbox.SECRET
            }, MyHelpers.dropbox.getParams())

            var client = new Dropbox.Client(options)

            if (options.access_token) {
                client._oauth.processRedirectParams(options)
                client.authStep = Dropbox.Client.DONE
            }

            return client
        },

        auth: function() {
            var client = this.getClient()

            client.authDriver(new Dropbox.AuthDriver.WinRT())
            client.authenticate()
        },

        sync: function (callback) {
            if (this.getClient().isAuthenticated()) {
                this.getClient().getAccountInfo(function (error, accountInfo) {
                    console.log(accountInfo);
                });
            } else {
                this.auth()
            }
        }
    }
}