Node js Streams: 'close' vs 'finish' event

Question

What is the difference between 'close' and 'finish' events for NodeJS Writable stream?

If we suppose that we have a writable stream that write to disk, are both 'close' and 'finish' events activating after the data is persisted to the disk or not?

Answer 1

With finish when all data is written to the stream but the stream may not be closed. After which a close will be emitted once file is closed. Hence finish will fire before close.

For example:

const writer = getWritableStreamSomehow();
for (let i = 0; i < 100; i++) {
    writer.write(`hello, #${i}!\n`);
}
writer.on('finish', () => {
    console.log('All data is written but file might NOT be closed');
});
writer.on('close', () => {
  console.log('All data written and file is closed');
});
writer.end('This is the end\n');

We can say writing a file involves Opening the file, Writting data to the File and Closing the file.

Finish will be emitted after finishing writing to the file and close after closing the file.