Geocoding, google maps.Error in script

I am using this function initMap in onload function it works for me i hope it will helpful for you

function initMap() {
            map = new google.maps.Map(document.getElementById('mapSection'), {
                center: { lat: 13.0480787, lng: 79.9288088 },
                zoom: 10, 
                mapTypeId: google.maps.MapTypeId.ROADMAP,
                zoomControl: true,
                zoomControlOptions: {
                    position: google.maps.ControlPosition.LEFT_CENTER
                },

            });

         // Create the search box and link it to the UI element.
  var input = document.getElementById('pac-input');
  var searchBox = new google.maps.places.SearchBox(input);
  map.controls[google.maps.ControlPosition.TOP_LEFT].push(input);

  // Bias the SearchBox results towards current map's viewport.
  map.addListener('bounds_changed', function() {
    searchBox.setBounds(map.getBounds());
    var bounds = map.getBounds();
  });

  var markers = [];
  var geocoder = new google.maps.Geocoder();

  searchBox.addListener('places_changed', function() {
    var places = searchBox.getPlaces();

    if (places.length == 0) {
      return;
    }
    geocodeAddress(geocoder, map);    
    // Clear out the old markers.
      markers.forEach(function(marker) {
      marker.setMap(null);
    });
    markers = [];  
    // For each place, get the icon, name and location.
    var bounds = new google.maps.LatLngBounds();
    map.fitBounds(bounds);
  });
  // [END region_getplaces]


  function geocodeAddress(geocoder, resultsMap) {

              var address = document.getElementById('pac-input').value;
              geocoder.geocode({'address': address}, function(results, status) {
                if (status === google.maps.GeocoderStatus.OK) {

                } else {
                  alert('Geocode was not successful for the following reason: ' + status);
                }
              });
            }
}

and if you want Marker on map use this function

function create_Marker(lat, lan, drivername, indx) {

     var MARKER = new google.maps.Marker({
        position : new google.maps.LatLng(lat, lan),
        map : MAP,
        icon : "images/car.png",
        title : drivername,
        animation : google.maps.Animation.DROP
    });
    MARKER_List.push(MARKER);
    google.maps.event.addListener(MARKER, 'click', (function(marker, indx) {
        return function() {
            infowindow.setContent("<div class='content' style='max-height:300px; font-size:12px;';'>" + drivername
                    + "</div>");
            infowindow.open(MAP, marker);
        }
    })(MARKER, indx));
}