Google Maps DomListener Causing Error After Going to Different Page

Question

I am having an issue where the dom listener at the bottom of my google maps function in an external Javascript file is causing a "google is not defined" console error. This happens when I go to a different HTML page on my website that also accesses script in the external file. I believe it is because the DomListener is outside the function however the function does not work if the dom listener is inside the function. Can someone please help me with where to put this DomListener to stop this error occurring? My code is below.

Thankyou very much, Anthony

function validateEmail() {
var email = form.emailaddress.value;
if (form.firstname.value == "") { 
document.getElementById("emailInvalid").style.visibility = "visible";   
return false;
} return true;
}

function initialize() {
  var myLatlng1 = new google.maps.LatLng(-25.363882,150.044922);
  var myLatlng2 = new google.maps.LatLng(-25.363882,152.044922);
  var mapOptions = {
    zoom: 6,
    center: myLatlng1
  };

  var map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);

  var contentString1 = 'Mott Park'
  var contentString2 = 'Kilpa Park'

  var infowindow = new google.maps.InfoWindow({
    });

  var marker1 = new google.maps.Marker({
  position: myLatlng1,
  map: map,
  title: 'Park'
  });
  var marker2 = new google.maps.Marker({
      position: myLatlng2,
      map: map,
      title: 'Water'
  });
    google.maps.event.addListener(marker1, 'click', function initialize() {
        infowindow.close();//hide the infowindow
        infowindow.setContent(contentString1);//update the content for this marker
        infowindow.open(map, marker1);

  });
    google.maps.event.addListener(marker2, 'click', function initialize() {
       infowindow.close();//hide the infowindow
       infowindow.setContent(contentString2);//update the content for this marker
       infowindow.open(map, marker2);
  });
}
google.maps.event.addDomListener(window, 'load', initialize); 

Answer 1

Here a possible duplicate:

"google is not defined" when using Google Maps V3 in Firefox remotely

I think its might be a placement problem similar to Diego Pino in the thread.