Many a times when you are using an external javascript library into your winjs application, you come across apis that expect a parameter as ArrayBuffer. Windows storage apis like FileIO.readBufferAsync return IBuffer. In such case, How do one read the contents of a file into ArrayBuffer?

There are multiple solutions for this. One of the solution that I have come across is to read the DOM ‘File’ object using WinJS.xhr.

        var storage = Windows.Storage;
        storage.StorageFile.getFileFromApplicationUriAsync(new Windows.Foundation.Uri('ms-appx:///images/logo.png')).then(function ongetfile(file)
        {
            var blob = MSApp.createFileFromStorageFile(file);
            var url = URL.createObjectURL(blob, { oneTimeOnly: true });
            return WinJS.xhr({ url: url, responseType: 'arraybuffer' });
        }).then(function onreadbuffer(req)
        {
            var arrayBuffer = req.response;
        }).then(null, function onerror(error)
        {
            // TODO: handle error
        });