index.html

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>My Google Map</title>
  <style>
    #map {
      height: 600px;
      width: 100%;
    }
  </style>
</head>

<body>
  <h1>explore4U Test map</h1>
  <form>
    <input type="text" id="API_KEY" placeholder="Enter your API Key">
    <input type="submit" value="Enter" onclick="passvalue()">
  </form>

  <div id="map"></div>

  <script type="text/javascript" src="./scripts/data.js"></script>
  <script type="text/javascript" src="./scripts/index.js"></script>
  <script async defer id="result"></script>
  <script>
    document.getElementById("result").src = "https://maps.googleapis.com/maps/api/js?key=" + localStorage.getItem("API_KEY") + "&callback=initMap";
  </script>

  <!-- <script async defer src="https://maps.googleapis.com/maps/api/js?key={{API_KEY}}&callback=initMap"> -->
  <!-- </script> -->
</body>

</html>