nodejs stream pipeline with custom transform
const fs = require('fs'); const { pipeline, Transform } = require('stream'); const readStream = fs.createReadStream("text.txt", { flags: 'r', encoding: 'utf-8', autoClose: true, }); const writeStream = fs.createWriteStream("text2.txt", { flags: 'w', encoding: 'utf-8', autoClose: true, }); const transformStream = new Transform({ //Transform data to filter for even numbers transform(chunk, enc, cb) { const data = chunk.toString().split(" ").filter(value => !(parseInt(value) & 1)); cb(null, data.join(" ")); } }); pipeline(readStream, transformStream, writeStream, (err) => { if(err) console.error(err); else console.error("success"); //writeStream has written only even numbers from readStream })