Office.Slice interface 
Represents a slice of a document file. The Slice object is accessed with the File.getSliceAsync method.
Properties
| data | Gets the raw data of the file slice in  | 
| index | Gets the zero-based index of the file slice. | 
| size | Gets the size of the slice in bytes. | 
Property Details
data
Gets the raw data of the file slice in Office.FileType.Text or Office.FileType.Compressed format as specified by the fileType parameter of the call to the Document.getFileAsync method.
data: any;Property Value
any
Remarks
Files in the "compressed" format will return a byte array that can be transformed to a Base64-encoded string if required.
index
Gets the zero-based index of the file slice.
index: number;Property Value
number
size
Gets the size of the slice in bytes.
size: number;Property Value
number