test.js

const createCsvWriter = require('csv-writer').createObjectCsvWriter
const fs = require('fs')
const readline = require('readline')

const records = [
    {sku: 'abc123', sellerId: '123456'},
    {sku: 'def123', sellerId: '789456'},
    {sku: 'yut741', sellerId: '741852'}
]

const INVALID_SKUS_FILE = 'invalid_skus.csv'

const csvWriter = createCsvWriter({
    path: INVALID_SKUS_FILE,
    header: [
        {id: 'sku', title: 'sku'},
        {id: 'sellerId', title: 'seller_id'}
    ],
    append: true
})

//delete the already existing file
fs.unlinkSync(INVALID_SKUS_FILE)

//write file
for(let i = 0; i < 3; i++){
    csvWriter.writeRecords(records)
}

const csvReader = readline.createInterface({
    input: fs.createReadStream(INVALID_SKUS_FILE)
})


const csvLineToObject = line => {
    const values = line.split(",")

    return {
        sku: values[0],
        seller_id: values[1]
    }
}

csvReader.on("line", line => console.log(csvLineToObject(line)))

// csvReader.readLines = fn => {
//     on("line", fn)
// }

// csvReader.readLines(line => console.log(csvLineToObject(line)))