Dynamic GeoJSON renders on HERE API for JavaScript engine

// define and initialize HERE GeoJSON reader

let reader = new H.data.geojson.Reader(null, {
  disableLegacyMode: true,
  style: function (mapObject) {
    if (mapObject instanceof H.map.Polyline) {
      let style = getTrafficBasedStyle(parseFloat(mapObject.data.CONGESTION_FACTOR));
      mapObject.setStyle(style);
    }
  }
});

let geoJsonLayer_HERE = reader.getLayer();

// Please note a couple of points HERE
// 1- I initially did set the geoJOSN reader to null, and will be set later based on user input or interactions
// 2- I initially set the style to a function that returns a variable style based on the GeoJOSN feature properties value

// add HERE geoJSON reader layer to the map to it can be ready to display the features once we set the source
map.addLayer(geoJsonLayer_HERE);

async function init_GeoJSON(file_GeoJSON) {
  const response = await fetch(file_GeoJSON);
  const data = await response.json();
  return data;
}

function getTrafficBasedStyle(congestionFactor) {
  let style;

  if (congestionFactor <= 0.5) {
    style = {
      strokeColor: '#61ba72', //green
      lineWidth: 3
    };
  } else if (congestionFactor > 0.5 && congestionFactor <= 0.75) {
    style = {
      strokeColor: '#fecf00', //yellow
      lineWidth: 4
    };
  } else if (congestionFactor > 0.75) {
    style = {
      strokeColor: '#ea232d', //red
      lineWidth: 5
    };
  }

  return style;
}

// make sure the execute the following logic whenever there is any user input/interaction that changes the geoJSON datasource and/or on the initialization
let geoJSON_data = await init_GeoJSON(`../output.geojson`);
geoJsonLayer_HERE.getProvider().getRootGroup().removeAll();
reader.parseData(geoJSON_data);