<script>
var GOOGLE_MAP_KEY = "prdukcniklic";

if(productioion == false){
    GOOGLE_MAP_KEY = "testklic";
}

function loadScript() {
  var script = document.createElement('script');
  script.type = 'text/javascript';
  script.src = 'https://maps.googleapis.com/maps/api/js?v=3' +
      '&key=' + GOOGLE_MAP_KEY +'&callback=initialize'; //& needed
  document.body.appendChild(script);
}

window.onload = loadScript;
</script>