document.getElementById("myBtn").addEventListener("click", function () {
    download("http://cordova.apache.org/static/img/cordova_bot.png", "data", "new_file");
});

function download(URL, Folder_Name, File_Name) {
    window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, fileSystemSuccess, fileSystemFail);

    function fileSystemSuccess(fileSystem) {
        var download_link = encodeURI(URL);
        ext = download_link.substr(download_link.lastIndexOf('.') + 1); //Get extension of URL

        var directoryEntry = fileSystem.root; // to get root path of directory
        directoryEntry.getDirectory(Folder_Name, {
            create: true,
            exclusive: false
        }, onDirectorySuccess, onDirectoryFail); // creating folder in sdcard
        var rootdir = fileSystem.root;
        var fp = rootdir.toURL();
        fp = fp + "/" + Folder_Name + "/" + File_Name + "." + ext; // fullpath and name of the file which we want to give
        filetransfer(download_link, fp);
    }

    function onDirectorySuccess(parent) {
        // Directory created successfuly
    }

    function onDirectoryFail(error) {
        alert("Unable to create new directory: " + error.code);
    }

    function fileSystemFail(evt) {
        //Unable to access file system
        alert(evt.target.error.code);
    }
}

function filetransfer(download_link, fp) {
    var fileTransfer = new FileTransfer();
    fileTransfer.download(download_link, fp,
        function (entry) {
            alert("download complete: " + entry.fullPath);
            //cordova.plugins.imagesaver.saveImageToGallery(entry.fullPath, successCallback, errorCallback);
        },
        function (error) {
            alert("download error source " + error.source);
        }
    );
}

function download() {
    window.requestFileSystem(window.TEMPORARY, 5 * 1024 * 1024, function (fs) {

        var url = 'http://cordova.apache.org/static/img/cordova_bot.png';
        fs.root.getFile('downloaded-image.png', {
            create: true,
            exclusive: false
        }, function (fileEntry) {
            file_transfer(fileEntry, encodeURI(url), true);

        }, onErrorCreateFile);

    }, onErrorLoadFs);
}

function onErrorLoadFs(msg){
    alert(msg);
}

function onErrorCreateFile(msg){
    alert(msg);
}

function file_transfer(fileEntry, uri, readBinaryData) {

    var fileTransfer = new FileTransfer();
    var fileURL = fileEntry.toURL();

    fileTransfer.download(
        uri,
        fileURL,
        function (entry) {
            alert("download complete: " + entry.toURL());

            if (readBinaryData) {
                // Read the file...
                readBinaryFile(entry);
            } else {
                // Or just display it.
                displayImageByFileURL(entry);
            }

        },
        function (error) {
            alert("download error source " + error.source);
            alert("download error target " + error.target);
            alert("upload error code" + error.code);
        },
        null, // or, pass false
        {
            //headers: {
            //    "Authorization": "Basic dGVzdHVzZXJuYW1lOnRlc3RwYXNzd29yZA=="
            //}
        }
    );
}