let { Duplex } = require('stream')

// 该流可读可写；相互独立
class MyDuplex extends Duplex {
    constructor(source) {
        super()
        this.source = source
    }
    _read() {
        let data = this.source.shift() || null
        this.push(data)
    }
    _write(chunk, en, done) {
        process.stdout.write(chunk.toString())
        process.nextTick(done)
    }
}

let source = ['a', 'b', 'c']
let myDuplex = new MyDuplex(source)

myDuplex.on('data', (chunk) => {
    console.log(chunk.toString());
})

myDuplex.write('写入的数据', () => {
    console.log(111);
})