文件阅读器循环问题

Question

    readFile : function(files)
    {
        for(x = 0; x < files.length; x = x + 1) {
            var file = files[x];
            (function(file){   
                var reader = new FileReader();
                reader.readAsDataURL(file);

                reader.onload = function(e) {
                    console.log(e.target.result);
                    console.log(file.name);
                }
            })(file);          

        }
    }
 var fileObjects = document.querySelectorAll('input[type=file]'), i;

this.readFile(fileObjects)

收到此错误

Failed to execute 'readAsDataURL' on 'FileReader': parameter 1 is not of type 'Blob'.