Cannot get my polyline drawn or visible - google-maps-api-3

Question

I try to draw a polyline according to this example:
https://developers.google.com/maps/documentation/javascript/examples/geometry-encodings.
My map is displayed, markers are displayed as well but the polyline is not drawn, or not visible.
I don't see what's wrong.
My javascript is:
<script src="https://maps.googleapis.com/maps/api/js?v=3.exp&signed_in=true&libraries=geometry"></script>
$( document ).ready(function($) {
var map;
var poly;
var iconBase = 'https://maps.google.com/mapfiles/kml/shapes/';
var ndgIconBase = 'http://example.com/img/';
var clickMarker;
nextWaypoint = parseInt(document.getElementById('agpoiwaypoints_size').innerHTML, 10);
countWaypoint = nextWaypoint;
function initialize() {
var mapCanvas = document.getElementById('map-canvas');
var content;
content = document.getElementById('agpoi-0-lat').innerHTML
var lat0 = parseFloat(content.substr(content.indexOf(":")+1));
content = document.getElementById('agpoi-0-lng').innerHTML
var lng0 = parseFloat(content.substr(content.indexOf(":")+1));
content = document.getElementById('agpoi-1-lat').innerHTML
var lat1 = parseFloat(content.substr(content.indexOf(":")+1));
content = document.getElementById('agpoi-1-lng').innerHTML
var lng1 = parseFloat(content.substr(content.indexOf(":")+1));
var mapOptions = {
center: new google.maps.LatLng((lat1 + lat0) / 2, (lng1 + lng0) / 2),
zoom: 18,
mapTypeId: google.maps.MapTypeId.ROADMAP
}
map = new google.maps.Map(mapCanvas, mapOptions);
var polyOptions = {
strokeColor: '#000000',
strokeOpacity: 1.0,
strokeWeight: 3,
map: map
};
poly = new google.maps.Polyline(polyOptions);
new google.maps.Marker({
position: {lat: lat0, lng: lng0},
map: map,
icon: ndgIconBase + 'myLogo.png'
});
new google.maps.Marker({
position: {lat: lat1, lng: lng1},
map: map,
icon: ndgIconBase + 'myLogo.png'
});
google.maps.event.addListener(map, 'click', function(e) {
placeMarker(e.latLng, map);
});
var position = {lat: lat0, lng: lng0};
var path = poly.getPath();
path.push(position);
var content;
for (i = 0; i < countWaypoint; i++) {
content = document.getElementById("agpoiwaypoints-" + i + "-latitude").value;
lat = parseFloat(content);
content = document.getElementById("agpoiwaypoints-" + i + "-longitude").value;
lng = parseFloat(content);
position = {lat: lat, lng: lng};
new google.maps.Marker({
position: position,
map: map
});
path = poly.getPath();
path.push(position);
}
position = {lat: lat1, lng: lng1};
path = poly.getPath();
path.push(position);
}
google.maps.event.addDomListener(window, 'load', initialize);
google.maps.event.addDomListener(window, 'click', placeMarker);
function placeMarker(position, map) {
if (clickMarker == 0) {
clickMarker = new google.maps.Marker({
position: position,
map: map
});
} else {
clickMarker.setPosition( position );
}
}
$("body").on("click", ".remove_agpoiwaypoint", function (e) {
e.preventDefault();
});
$("body").on("click", ".add_agpoiwaypoint", function (e) {
e.preventDefault();
var path = poly.getPath();
var position = clickMarker.getPosition();
path.push(position);
});
});

Answer 1

When you do path = poly.getPath(); you're simply getting an array and assigning it to a variable called path. Then when you do path.push(position); you're merely adding things into that variable... it's not updating the polyline's path.
Instead you then need to update the polyline too, e.g. then you could also do
poly.setPath(path);