Adding State to Controls

Sample code for Google Maps Platform JavaScript API author(s): Justin Poehnelt

HTML

<!doctype html>
<!--
 @license
 Copyright 2019 Google LLC. All Rights Reserved.
 SPDX-License-Identifier: Apache-2.0
-->
<html>
  <head>
    <title>Adding State to Controls</title>

    <!-- jsFiddle will insert css and js -->
  </head>
  <body>
    <div id="map"></div>

    <!-- 
      The `defer` attribute causes the script to execute after the full HTML
      document has been parsed. For non-blocking uses, avoiding race conditions,
      and consistent behavior across browsers, consider loading using Promises. See
      https://developers.google.com/maps/documentation/javascript/load-maps-js-api
      for more information.
      -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly"
      defer
    ></script>
  </body>
</html>

CSS

/**
 * @license
 * Copyright 2019 Google LLC. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0
 */
/* 
 * Always set the map height explicitly to define the size of the div element
 * that contains the map. 
 */
#map {
  height: 100%;
}

/* 
 * Optional: Makes the sample page fill the window. 
 */
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

#goCenterUI,
#setCenterUI {
  background-color: #fff;
  border: 2px solid #fff;
  border-radius: 3px;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
  cursor: pointer;
  float: left;
  margin-bottom: 22px;
  text-align: center;
}

#goCenterText,
#setCenterText {
  color: rgb(25, 25, 25);
  font-family: Roboto, Arial, sans-serif;
  font-size: 15px;
  line-height: 25px;
  padding-left: 5px;
  padding-right: 5px;
}

#setCenterUI {
  margin-left: 12px;
}

JavaScript

/**
 * @license
 * Copyright 2019 Google LLC. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0
 */
let map;
const chicago = { lat: 41.85, lng: -87.65 };

/**
 * The CenterControl adds a control to the map that recenters the map on
 * Chicago.
 */
class CenterControl {
  map_;
  center_;
  constructor(controlDiv, map, center) {
    this.map_ = map;
    // Set the center property upon construction
    this.center_ = new google.maps.LatLng(center);
    controlDiv.style.clear = "both";

    // Set CSS for the control border
    const goCenterUI = document.createElement("button");

    goCenterUI.id = "goCenterUI";
    goCenterUI.title = "Click to recenter the map";
    controlDiv.appendChild(goCenterUI);

    // Set CSS for the control interior
    const goCenterText = document.createElement("div");

    goCenterText.id = "goCenterText";
    goCenterText.innerHTML = "Center Map";
    goCenterUI.appendChild(goCenterText);

    // Set CSS for the setCenter control border
    const setCenterUI = document.createElement("button");

    setCenterUI.id = "setCenterUI";
    setCenterUI.title = "Click to change the center of the map";
    controlDiv.appendChild(setCenterUI);

    // Set CSS for the control interior
    const setCenterText = document.createElement("div");

    setCenterText.id = "setCenterText";
    setCenterText.innerHTML = "Set Center";
    setCenterUI.appendChild(setCenterText);
    // Set up the click event listener for 'Center Map': Set the center of
    // the map
    // to the current center of the control.
    goCenterUI.addEventListener("click", () => {
      const currentCenter = this.center_;

      this.map_.setCenter(currentCenter);
    });
    // Set up the click event listener for 'Set Center': Set the center of
    // the control to the current center of the map.
    setCenterUI.addEventListener("click", () => {
      const newCenter = this.map_.getCenter();

      if (newCenter) {
        this.center_ = newCenter;
      }
    });
 ...