sheetjs/docbits/31_writestream.md

Streaming Write

The streaming write functions are available in the XLSX.stream object. They take the same arguments as the normal write functions but return a readable stream. They are only exposed in node.

• XLSX.stream.to_csv is the streaming version of XLSX.utils.sheet_to_csv.
• XLSX.stream.to_html is the streaming version of XLSX.utils.sheet_to_html.

nodejs convert to CSV and write file (click to show)

var output_file_name = "out.csv";
var stream = XLSX.stream.to_csv(worksheet);
stream.pipe(fs.createWriteStream(output_file_name));

https://github.com/sheetjs/sheetaki pipes write streams to nodejs response.