Fetch asynchronous multiple requests.

async.js

var fs = require('fs');
var axios = require('axios');
var async = require('async');
const Bank = require('./models/Bank');
var codes;
var counter = 0;
const mongoose = require('mongoose');
mongoose.Promise = global.Promise;

module.exports = () => {
  fs.readFile('./server/IFSC-list.txt', (err, data) => {
    if (err) throw err;
    codes = data.toString().split("\n");
    async.eachSeries(codes, (ifsc, callback) => {
      console.log(ifsc, 'ON');
      axios.get(`https://ifsc.razorpay.com/${ifsc}`)
      .then(function (response) {
        const {IFSC, BANK, CITY} = response.data;
        var newBank = new Bank({
          IFSC,
          BANK,
          CITY
        });
        newBank.save();
        console.log('saved', ++counter);
        callback();
      })
      .catch(function (error) {
        console.log(error);
      });
    });
  });
}