While ArrayBuffer, Uint8Array and other BufferSource are “binary data”, a Blob represents “binary data with type”. That makes Blobs convenient for upload/download operations, that are so common in . Changing “dataType” parameter to “text”, does not help, neither changing it to any other jQuery supported Ajax data type. Problem here is that jQuery still does not support HTML5 XMLHttpRequest Level 2 binary data type requests – there is even a bug in jQuery bug tracker, which asks for. The getAsBinary method allows to access the file's data in raw binary format. Note: This method is obsolete; you should use the FileReader method readAsBinaryString() or readAsArrayBuffer() instead.