Trying to ue devisestorage api

webapp.js

(function () {
    var pickAnything = document.querySelector("#pick-anything");
    if (pickAnything) { 
  
    pickAnything.onclick = function() {
			var storage = navigator.getDeviceStorage("sdcard");
			
            cursor = storage.enumerate();
            
        	cursor.onerror = function() {
                console.error("Error in DeviceStorage.enumerate()", cursor.error.name); //console shows this error
	       };
            

	       cursor.onsuccess = function() {
            if (!cursor.result) 
                alert('something');
            }
            
            alert(cursor.result);
            var file = cursor.result;

 
            // Show file
            alert(file.name);
            console.log(file.name);
		
        };
    }
    
})();