infinite_scroll_es.js

let data = [];
try {
  let query = {
    index: 'index-name',
    body: {
      query: {
        bool: {
            // ...
        }
      },
      sort: [{ "unique-property-on-index": "asc" }], // can be both asc & desc
      size: 100 // data to retrieve at a time
    }
  };

  var lastHits;
  do {
    lastHits = (await es.client.search(query)).body.hits.hits;
    if (lastHits.length > 0) {
      data = data.concat(lastHits);
      query.body["search_after"] = [lastHits.pop()._source["unique-property-on-index"]];
    }
  } while (lastHits.length > 0);
   
  // you get your results on "data" array