multiplyCsv.js

const csv = require("csv-parser");
const fs = require("fs");
const parseArgs = require("minimist");
const createCsvWriter = require("csv-writer").createObjectCsvWriter;
const _ = require("lodash");

function printProgress(progress) {
  process.stdout.clearLine();
  process.stdout.cursorTo(0);
  process.stdout.write(progress);
}

function multiplyCsv() {
  const args = parseArgs(process.argv.slice(2));

  let csvData = [];
  let multipliedData = [];

  const { input, n = 10, output } = args;

  if (!input) {
    throw new Error("CSV input is necessary");
  }

  if (!output) {
    throw new Error("CSV output is necessary");
  }

  const fileStream = fs
    .createReadStream(input)
    .pipe(csv())
    .on("data", row => {
      csvData = [...csvData, row];
    });

  fileStream.on("end", () => {
    if (csvData.length > 0 && n > 0) {
      for (let index = 0; index < n; index++) {
        printProgress(`${((index / n) * 100).toFixed(4)}% apended`);
        multipliedData = [...multipliedData, ..._.shuffle(csvData)];
      }

      if (multipliedData.length) {
        const header = Object.keys(csvData[0]).map(key => ({
          id: key,
          title: key
        }));
        const csvWriter = createCsvWriter({
          path: output,
          header
        });

        process.stdout.write(
          `beginning to write ${multipliedData.length} lines`
        );

        csvWriter
          .writeRecords(multipliedData)
          .then(() => console.log("The CSV file was written successfully"));
      } else {
        console.error("multiplied data was empty");
      }
    } else {
      console.error("Input was empty");
    }
  });
}

multiplyCsv();