index.html

<!--AIzaSyCBTHJeGSBSJr37_MjkMhuI3g4sIdNysU8-->
<!DOCTYPE html>
<html>

<head>
    <title>Simple Map</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>
    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script src="http://d3js.org/d3.v3.js"></script>
    <script src="./index.js"></script>


</head>

<body>
    <div id="map"></div>


    <!-- Async script executes immediately and must be after any DOM elements used in callback. -->
    <script
        src="https://maps.googleapis.com/maps/api/js?key=YOUR_KEY&callback=initMap&v=weekly"
        async></script>
</body>

</html>