Waypoints in Directions

function initMap(): void {
  const directionsService = new google.maps.DirectionsService();
  const directionsRenderer = new google.maps.DirectionsRenderer();
  const map = new google.maps.Map(
    document.getElementById("map") as HTMLElement,
    {
      zoom: 6,
      center: { lat: 41.85, lng: -87.65 },
    }
  );

  directionsRenderer.setMap(map);

  (document.getElementById("submit") as HTMLElement).addEventListener(
    "click",
    () => {
      calculateAndDisplayRoute(directionsService, directionsRenderer);
    }
  );
}

function calculateAndDisplayRoute(
  directionsService: google.maps.DirectionsService,
  directionsRenderer: google.maps.DirectionsRenderer
) {
  const waypts: google.maps.DirectionsWaypoint[] = [];
  const checkboxArray = document.getElementById(
    "waypoints"
  ) as HTMLSelectElement;

  for (let i = 0; i < checkboxArray.length; i++) {
    if (checkboxArray.options[i].selected) {
      waypts.push({
        location: (checkboxArray[i] as HTMLOptionElement).value,
        stopover: true,
      });
    }
  }

  directionsService
    .route({
      origin: (document.getElementById("start") as HTMLInputElement).value,
      destination: (document.getElementById("end") as HTMLInputElement).value,
      waypoints: waypts,
      optimizeWaypoints: true,
      travelMode: google.maps.TravelMode.DRIVING,
    })
    .then((response) => {
      directionsRenderer.setDirections(response);

      const route = response.routes[0];
      const summaryPanel = document.getElementById(
        "directions-panel"
      ) as HTMLElement;

      summaryPanel.innerHTML = "";

      // For each route, display summary information.
      for (let i = 0; i < route.legs.length; i++) {
        const routeSegment = i + 1;

        summaryPanel.innerHTML +=
          "<b>Route Segment: " + routeSegment + "</b><br>";
        summaryPanel.innerHTML += route.legs[i].start_address + " to ";
        summaryPanel.innerHTML += route.legs[i].end_address + "<br>";
        summaryPanel.innerHTML += route.legs[i].distance!.text + "<br><br>";
      }
    })
    .catch((e) => window.alert("Directions request failed due to " + status));
}

declare global {
  interface Window {
    initMap: () => void;
  }
}
window.initMap = initMap;
index.ts

function initMap() {
  const directionsService = new google.maps.DirectionsService();
  const directionsRenderer = new google.maps.DirectionsRenderer();
  const map = new google.maps.Map(document.getElementById("map"), {
    zoom: 6,
    center: { lat: 41.85, lng: -87.65 },
  });

  directionsRenderer.setMap(map);
  document.getElementById("submit").addEventListener("click", () => {
    calculateAndDisplayRoute(directionsService, directionsRenderer);
  });
}

function calculateAndDisplayRoute(directionsService, directionsRenderer) {
  const waypts = [];
  const checkboxArray = document.getElementById("waypoints");

  for (let i = 0; i < checkboxArray.length; i++) {
    if (checkboxArray.options[i].selected) {
      waypts.push({
        location: checkboxArray[i].value,
        stopover: true,
      });
    }
  }

  directionsService
    .route({
      origin: document.getElementById("start").value,
      destination: document.getElementById("end").value,
      waypoints: waypts,
      optimizeWaypoints: true,
      travelMode: google.maps.TravelMode.DRIVING,
    })
    .then((response) => {
      directionsRenderer.setDirections(response);

      const route = response.routes[0];
      const summaryPanel = document.getElementById("directions-panel");

      summaryPanel.innerHTML = "";

      // For each route, display summary information.
      for (let i = 0; i < route.legs.length; i++) {
        const routeSegment = i + 1;

        summaryPanel.innerHTML +=
          "<b>Route Segment: " + routeSegment + "</b><br>";
        summaryPanel.innerHTML += route.legs[i].start_address + " to ";
        summaryPanel.innerHTML += route.legs[i].end_address + "<br>";
        summaryPanel.innerHTML += route.legs[i].distance.text + "<br><br>";
      }
    })
    .catch((e) => window.alert("Directions request failed due to " + status));
}

window.initMap = initMap;
index.js

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

#container {
  height: 100%;
  display: flex;
}

#sidebar {
  flex-basis: 15rem;
  flex-grow: 1;
  padding: 1rem;
  max-width: 30rem;
  height: 100%;
  box-sizing: border-box;
  overflow: auto;
}

#map {
  flex-basis: 0;
  flex-grow: 4;
  height: 100%;
}

#directions-panel {
  margin-top: 10px;
}
style.css

<html>
  <head>
    <title>Waypoints in Directions</title>

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>
  </head>
  <body>
    <div id="container">
      <div id="map"></div>
      <div id="sidebar">
        <div>
          <b>Start:</b>
          <select id="start">
            <option value="Halifax, NS">Halifax, NS</option>
            <option value="Boston, MA">Boston, MA</option>
            <option value="New York, NY">New York, NY</option>
            <option value="Miami, FL">Miami, FL</option>
          </select>
          <br />
          <b>Waypoints:</b> <br />
          <i>(Ctrl+Click or Cmd+Click for multiple selection)</i> <br />
          <select multiple id="waypoints">
            <option value="montreal, quebec">Montreal, QBC</option>
            <option value="toronto, ont">Toronto, ONT</option>
            <option value="chicago, il">Chicago</option>
            <option value="winnipeg, mb">Winnipeg</option>
            <option value="fargo, nd">Fargo</option>
            <option value="calgary, ab">Calgary</option>
            <option value="spokane, wa">Spokane</option>
          </select>
          <br />
          <b>End:</b>
          <select id="end">
            <option value="Vancouver, BC">Vancouver, BC</option>
            <option value="Seattle, WA">Seattle, WA</option>
            <option value="San Francisco, CA">San Francisco, CA</option>
            <option value="Los Angeles, CA">Los Angeles, CA</option>
          </select>
          <br />
          <input type="submit" id="submit" />
        </div>
        <div id="directions-panel"></div>
      </div>
    </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>
index.html