event finish

调用 [stream.end()][stream-end] 且缓冲数据都已传给底层系统之后触发。

const writer = getWritableStreamSomehow();
for (let i = 0; i < 100; i++) {
  writer.write(`写入 #${i}!\n`);
}
writer.on('finish', () => {
  console.error('写入已完成');
});
writer.end('写入结尾\n');