写数据流

const fs = require('fs');

let str = '';
for (let i = 0; i < 1e4; i++) {
  str += `写入数据${i}\n`;
}

const writeStream = fs.createWriteStream('./data/output.txt');
writeStream.write(str);
writeStream.end();
writeStream.on('finish', () => {
  console.log('write success');
});
writeStream.on('error', (err) => {
  console.err(err);
});

读数据流

const fs = require('fs');

let count = 0;
let str = '';
const readStream = fs.createReadStream('./data/output.txt');

readStream.on('data', (data) => {
  str += data;
  count += 1;
});
readStream.on('end', () => {
  console.log('read file end', str, count);
});
readStream.on('error', (err) => {
  console.error(err);
});

管道流

const fs = require('fs');

const readStream = fs.createReadStream('./data/output.txt');
const writeStream = fs.createWriteStream('./data/output2.txt');

readStream.pipe(writeStream);