index.ts

/**
 * @license
 * Copyright 2019 Google LLC. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0
 */

// [START maps_layer_data_quakes_red]
let innerMap;

async function initMap() {
  (await google.maps.importLibrary("maps")) as google.maps.MapsLibrary;

  const mapElement = document.querySelector(
    "gmp-map"
  ) as google.maps.MapElement;

  innerMap = mapElement.innerMap;

  // Get the earthquake data (JSONP format)
  // This feed is a copy from the USGS feed, you can find the originals here:
  //   http://earthquake.usgs.gov/earthquakes/feed/v1.0/geojson.php
  const script = document.createElement("script");

  script.setAttribute(
    "src",
    "quakes.geo.json"
  );

  document.getElementsByTagName("head")[0].appendChild(script);

  // Add a basic style.
  innerMap.data.setStyle((feature) => {
    const mag = Math.exp(parseFloat(feature.getProperty("mag") as string)) * 0.1;
    return /** @type {google.maps.Data.StyleOptions} */ {
      icon: {
        path: google.maps.SymbolPath.CIRCLE,
        scale: mag,
        fillColor: "#f00",
        fillOpacity: 0.35,
        strokeWeight: 0,
      },
    };
  });
}

// Defines the callback function referenced in the jsonp file.
function eqfeed_callback(data: any) {
  innerMap.data.addGeoJson(data);
}

window.eqfeed_callback = eqfeed_callback;
initMap();
// [END maps_layer_data_quakes_red]