ExcelJs does not finish properly when using stream buffer like this:

@options.workbookOpts = {
#   filename: 'tmp/test.xlsx',
#   stream: @outputStream,
    useStyles: true,
    useSharedStrings: true
};

@workbook = new Excel.stream.xlsx.WorkbookWriter @options.workbookOpts
@worksheet = @workbook.addWorksheet('WSName')
@workbook.stream.pipe(@outputStream)

## add some rows

@workbook.commit()
.then (res) =>
 console.log("END")

On this line https://github.com/guyonroche/exceljs/blob/master/lib/stream/xlsx/workbook-writer.js#L320 you are listening for finish event which is correct for writeStreams (based on node.js doc: https://nodejs.org/api/stream.html#stream_event_finish)

But here in the StreamBuf class you are emitting end event instead:
https://github.com/guyonroche/exceljs/blob/master/lib/utils/stream-buf.js#L287

Possible solutions are:

1. Emit finish event instead. (Or emit both end and finish events?)
   PR: Fire finish event instead of end event on write stream #199

2. Don't listen for events on StreamBuf but on zipStream instead.
   PR: Listen for finish event on zip stream instead of middle stream #200

Sideinfo: end event is on readStreams instead.

Workaround: is to use stream: --writeStream-- option instead of piping (in my code it is commented out).