Code works in EDIT view and not SAVED page - dictionary

Question

My mission: Create a map from list such as :
When editing a SharePoint page (edit mode/view) the map throws no errors in the console. But as I go to view the final saved page the map I get this error in the console:
Event Page.aspx:668 Uncaught TypeError: Cannot read property 'get_current' of undefined
at retrieveListItems (Event Page.aspx:668)
at Event Page.aspx:789
This error points to this line :
var clientContext = new SP.ClientContext.get_current();
It seems like the PAGE is missing some resources that get added when I'm in EDIT MODE.
This code gets the info from the list to pass to the map script.
function retrieveListItems() {
var listName = "North East Events";
var clientContext = new SP.ClientContext.get_current();
var oList = clientContext.get_web().get_lists().getByTitle(listName);
this.website = clientContext.get_web();
var camlQuery = new SP.CamlQuery();
camlQuery.set_viewXml('<View><Query><Where><Geq><FieldRef Name=\'ID\'/>' +
'<Value Type=\'Number\'>1</Value></Geq></Where></Query><RowLimit>50</RowLimit></View>');
collListItem = oList.getItems(camlQuery);
clientContext.load(this.website);
clientContext.load(this.collListItem);
clientContext.executeQueryAsync(Function.createDelegate(this, onQuerySucceeded), Function.createDelegate(this, onQueryFailed));
}
function onQuerySucceeded(sender, args) {
var geocoder;
var map;
var bounds = new google.maps.LatLngBounds();
var listItemInfo = '';
var locations = [];
var listItemEnumerator = collListItem.getEnumerator();
while (listItemEnumerator.moveNext()) {
var oListItem = listItemEnumerator.get_current();
var eventName = oListItem.get_item('Title');
var eventAddress = oListItem.get_item('WorkAddress');
var eventURL = website.get_url() + '/' + 'Lists/North East Reports/DispForm.aspx?ID=' + oListItem.get_id();
var newLocations = [eventName, eventAddress, eventURL];
locations.push(newLocations);
}
google.maps.event.addDomListener(window, "load", initialize);
function initialize() {
map = new google.maps.Map(
document.getElementById("map_canvas"), {
center: new google.maps.LatLng(37.4419, -122.1419),
zoom: 13,
mapTypeId: google.maps.MapTypeId.ROADMAP
});
geocoder = new google.maps.Geocoder();
for (i = 0; i < locations.length; i++) {
geocodeAddress(locations, i);
}
}
function geocodeAddress(locations, i) {
var title = locations[i][0];
var address = locations[i][1];
var url = locations[i][2];
geocoder.geocode({
'address': locations[i][1]
},
function(results, status) {
if (status == google.maps.GeocoderStatus.OK) {
var marker = new google.maps.Marker({
icon: 'http://maps.google.com/mapfiles/ms/icons/blue.png',
map: map,
position: results[0].geometry.location,
title: title,
animation: google.maps.Animation.DROP,
address: address,
url: url
})
infoWindow(marker, map, title, address, url);
bounds.extend(marker.getPosition());
map.fitBounds(bounds);
} else {
alert("geocode of " + address + " failed:" + status);
}
});
}
function infoWindow(marker, map, title, address, url) {
google.maps.event.addListener(marker, 'click', function() {
var html = "<div><h3>" + title + "</h3><p>" + address + "<br></div><a href='" + url + "'>View location</a></p></div>";
iw = new google.maps.InfoWindow({
content: html,
maxWidth: 350
});
iw.open(map, marker);
});
}
function createMarker(results) {
var marker = new google.maps.Marker({
icon: 'http://maps.google.com/mapfiles/ms/icons/blue.png',
map: map,
position: results[0].geometry.location,
title: title,
animation: google.maps.Animation.DROP,
address: address,
url: url
})
bounds.extend(marker.getPosition());
map.fitBounds(bounds);
infoWindow(marker, map, title, address, url);
return marker;
}
}
function onQueryFailed(sender, args) {
alert('Request failed. ' + args.get_message() + '\n' + args.get_stackTrace());
}
retrieveListItems();