Google Maps Marker Cluster isn't working - wordpress

Question

For the life of me, I can not get this to work. I'm trying to pass the Marker Clusterers to my Google Map - but it's not working. I've got this map set up through Google Maps API and it's for a Wordpress website. The user can add locations using a Custom Post type. There are a lot of locations in close proximities, so I'm trying to use the MarkerCluster to lighten it up a bit. I've never used the MarkerCluster before, so it could be a small thing, too... not sure.
'var mc = new MarkerClusterer(map);' --This draws an error of: "Uncaught ReferenceError: MarkerClusterer is not defined"
Any insight? Any help is greatly appreciated!!
<?php // Index template
get_header(); ?>
<script src="https://maps.googleapis.com/maps/api/js?v=3.exp&sensor=false"></script>
<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=true"></script>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7/jquery.min.js"></script>
<div class="twelve column">
<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
<div class="intro">
<?php the_excerpt(); ?>
<hr>
</div>
<?php the_content(); ?>
<header class="clearfix"></header>
<div id="mapcanvas"></div>
<?php
// For creating multiple, customized loops.
// http://codex.wordpress.org/Class_Reference/WP_Query
$custom_query = new WP_Query('post_type=locations'); // exclude category 9
while($custom_query->have_posts()) : $custom_query->the_post(); ?>
<?php if(get_field('link')): ?>
<div>
<?php while(has_sub_field('link')): ?>
<div>
<p><?php the_sub_field('url'); ?></p>
</div>
<?php endwhile; ?>
</div>
<?php endif; ?>
<?php endwhile; ?>
<?php wp_reset_postdata(); // reset the query ?>
<?php
function get_single_term($post_id, $taxonomy)
{
$terms = wp_get_object_terms($post_id, $taxonomy);
if(!is_wp_error($terms)) {
return ''.$terms[0]->name.'';
}
}
$i = 0;
// For creating multiple, customized loops.
// http://codex.wordpress.org/Class_Reference/WP_Query
$custom_query = new WP_Query('post_type=location&posts_per_page=-1');
while($custom_query->have_posts()) : $custom_query->the_post();
$title = get_the_title(); // Location title
$map = get_field('location'); // ACF location contains address and coordinates
$terms = strip_tags( get_the_term_list( $post->ID, 'distributors', '', ' & ' )); // Get distributor terms and rm links
$info = '<strong>' . $title . '</strong><br>' . $map['address']; // Info window content
$link = get_field('link');
if($link){
$info .= '<br>'. $link .'';
}
$location[$i][0] = $title; // Store the post title
$location[$i][1] = $map['coordinates']; // Store the ACF coordinates
$location[$i][2] = json_encode($info); // Store info window content
$location[$i][3] = strip_tags( get_single_term( $post->ID, 'distributors' )); // Get first term for marker icon
$i ++;
endwhile; ?>
<?php wp_reset_postdata(); // reset the query ?>
<script>
$(function initialize() {
geocoder = new google.maps.Geocoder();
// Center map on our main location
var myLatLng = new google.maps.LatLng(41.583013,-93.63701500000002);
var bounds = new google.maps.LatLngBounds();
// https://developers.google.com/maps/documentation/javascript/styling
// Create an array of styles.
var styles = [
{
stylers: [
{ saturation: -99.9 }
]
}
];
// Create a new StyledMapType object, passing it the array of styles,
// as well as the name to be displayed on the map type control.
var styledMap = new google.maps.StyledMapType(styles, {name: 'exile'});
// Create a map object, and include the MapTypeId to add
// to the map type control.
var mapOptions = {
mapTypeId: 'roadmap',
center: myLatLng,
zoom: 14,
disableDefaultUI: false,
scrollwheel: true,
draggable: true
};
// Display a map on the page
var map = new google.maps.Map(document.getElementById("mapcanvas"), mapOptions);
var mc = new MarkerClusterer(map);
map.setTilt(45);
//Associate the styled map with the MapTypeId and set it to display.
map.mapTypes.set('exile', styledMap);
map.setMapTypeId('exile');
// Marker icons
typeObject = {
"Others" : {
"icon" : new google.maps.MarkerImage('http://exilebrewing.com/site/img/beer-mug.png', new google.maps.Size(18,26), new google.maps.Point(0,0), new google.maps.Point(9,26)),
"shadow" : new google.maps.MarkerImage('http://maps.google.com/mapfiles/shadow50.png', new google.maps.Size(40,34))
}
}
// http://wrightshq.com/playground/placing-multiple-markers-on-a-google-map-using-api-3/
// Multiple Markers
var markers = [
["Exile Brewing Co", 41.583013,-93.63701500000002,"Others"],
<?php
if (count($location)>0) {
foreach ($location as $key => $value){
if ($key < (count($location)-1)){
echo '["' . $location[$key][0] . '",' . $location[$key][1] . ',"' . $location[$key][3] . '"], ' . "\n";
} else {
echo '["' . $location[$key][0] . '",' . $location[$key][1] . ',"' . $location[$key][3] . '"]';
}
}
}
?>
];
var markers = [];
for (var i = 0; i < 100; i++) {
var latLng = new google.maps.LatLng(data.photos[i].latitude,
data.photos[i].longitude);
var marker = new google.maps.Marker({'position': latLng});
markers.push(marker);
}
var markerCluster = new MarkerClusterer(map, markers);
// Info Window Content
var infoWindowContent = [
["<strong>Exile Brewing Co.</strong><br>1514 Walnut Street, Des Moines"],
<?php
if (count($location)>0) {
foreach ($location as $key => $value){
if ($key < (count($location)-1)) {
echo '[' . $location[$key][2] . '], ' . "\n";
} else {
echo '[' . $location[$key][2] . ']';
}
}
}
?>
];
// Display multiple markers on a map
var infoWindow = new google.maps.InfoWindow(), marker, i;
// Loop through our array of markers & place each one on the map
for( i = 0; i < markers.length; i++ ) {
var position = new google.maps.LatLng(markers[i][1], markers[i][2]); // ACF coordinates
var icon = typeObject[markers[i][3]]['icon'];
var shadow = typeObject[markers[i][3]]['shadow'];
bounds.extend(position);
marker = new google.maps.Marker({
position: position,
map: map,
title: markers[i][0],
icon: icon,
shadow: shadow
});
// Allow each marker to have an info window
google.maps.event.addListener(marker, 'click', (function(marker, i) {
return function() {
infoWindow.setContent(infoWindowContent[i][0]);
infoWindow.open(map, marker);
}
})(marker, i));
// Automatically center the map fitting all markers on the screen
//map.fitBounds(bounds);
}
// Override our map zoom level once our fitBounds function runs (Make sure it only runs once)
var boundsListener = google.maps.event.addListener((map), 'bounds_changed', function(event) {
this.setZoom(15);
google.maps.event.removeListener(boundsListener);
});
});
</script>
<div id="map-canvas"></div>
<footer class="clearfix"></footer>
<?php endwhile;?>
<?php endif; ?>
</div>
</div>
<?php get_footer(); ?>

Answer 1

As per my comments :
You need to download the script ( here ) and then Include it in your page.
Marker clusterer is not a built-in feature of google maps , but an addon script ..
<script src="markerclusterer.js" type="text/javascript"></script>
or in the "correct" wordpress way :
wp_register_script( 'js_marker_clusterer', plugins_url( '/scripts/MarkerClusterer.js', __FILE__ ),'jquery' ); // or other dependencies descendents - preferably map JS or your custom.
wp_enqueue_script('js_marker_clusterer');
( change to your paths )
Also, look at the examples ( HERE ) and check their code ( and includes )

Answer 2

You need to include the third party marker clusterer script if you want to use it.
As specified in the documentation:
Note: Be sure to include markerclusterer.js or markerclusterer_packed.js in your HTML document.
<script src="/path/to/markerclusterer.js" type="text/javascript"></script>