readable.js

readable.js

const {Readable} = require('stream')

const inStream = new Readable( {
    read(size) {
        setTimeout(() => {
        this.push(String.fromCharCode(this.currentCharCode++))
        if (this.currentCharCode > 90) {
            this.push(null)
        }
    }, 100)
    }
});

inStream.currentCharCode = 65;
// not efficient as we push to stream and only then pipe
// inStream.push('hi')
// inStream.push(null)

// let's push on demand



inStream.pipe(process.stdout)