data.js

//require the Elasticsearch librray
const elasticsearch = require('elasticsearch');
// instantiate an Elasticsearch client
const client = new elasticsearch.Client({
   hosts: [ 'http://localhost:9200']
});

// ping the client to be sure Elasticsearch is up
client.ping({
     requestTimeout: 30000,
 }, function(error) {
 // at this point, eastic search is down, please check your Elasticsearch service
     if (error) {
         console.error('Elasticsearch cluster is down!');
     } else {
         console.log('Everything is ok');
     }
 });

// create a new index called scotch.io-tutorial. If the index has already been created, this function fails safely
client.indices.create({
  index: 'scotch.io-tutorial'
}, function(error, response, status) {
  if (error) {
      console.log(error);
  } else {
      console.log("created a new index", response);
  }
});

// // add a data to the index that has already been created
// client.index({
//   index: 'scotch.io-tutorial',
//   id: '1',
//   type: 'cities_list',
//   body: {
//       "Key1": "Content for key one",
//       "Key2": "Content for key two",
//       "key3": "Content for key three",
//   }
// }, function(err, resp, status) {
//   console.log(resp);
// });

const cities = require('./data/cities.json');
// declare an empty array called bulk
var bulk = [];
//loop through each city and create and push two objects into the array in each loop
//first object sends the index and type you will be saving the data as
//second object is the data you want to index
cities.forEach(city =>{
   bulk.push({index:{ 
                 _index:"scotch.io-tutorial", 
                 _type:"cities_list",
             }          
         })
  bulk.push(city)
})

//perform bulk indexing of the data passed
client.bulk({body: bulk}, function( err, response  ){ 
         if( err ){ 
             console.log("Failed Bulk operation".red, err) 
         } else { 
             console.log("Successfully imported %s".green, cities.length); 
         } 
});