get the elevation of a googlemaps' marker - google-maps

Question

I try to get the elevation of a point on a map, but the elevation function proposed by the googlemaps' API doesn't work and I don't know why.
It seems that the programm don't even get through the function.
Here my function :
var elevationService = new google.maps.ElevationService();
var requestElevation = {
'locations': gmarkers[0].getPosition()};
elevationService.getElevationForLocations(requestElevation, function(results, status) {
if (status == google.maps.ElevationStatus.OK) {
if (results[0]) {
document.getElementById('denivele_circuit').value = parseFloat(results[0].elevation.toFixed(1)) + "mètres";
}
} });

Answer 1

I get a javascript error with your code: Uncaught InvalidValueError: in property locations: not an Array
The locations property in the LocationElevationRequest must be an array.
from the documentation for google.maps.LocationElevationRequest object specification
An elevation request sent by the ElevationService containing the list of discrete coordinates (LatLngs) for which to return elevation data.
Properties
locations Type: Array
The discrete locations for which to retrieve elevations.
var requestElevation = {
'locations': [gmarkers[0].getPosition()]
};
proof of concept fiddle
code snippet:
var gmarkers = [];
function initialize() {
var 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
});
var marker = new google.maps.Marker({
position: map.getCenter(),
map: map
});
gmarkers.push(marker);
var elevationService = new google.maps.ElevationService();
var requestElevation = {
'locations': [gmarkers[0].getPosition()]
};
elevationService.getElevationForLocations(requestElevation, function(results, status) {
if (status == google.maps.ElevationStatus.OK) {
if (results[0]) {
document.getElementById('denivele_circuit').value = parseFloat(results[0].elevation.toFixed(1)) + " mètres";
}
}
});
}
google.maps.event.addDomListener(window, "load", initialize);
html,
body,
#map_canvas {
height: 100%;
width: 100%;
margin: 0px;
padding: 0px
}
<script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk"></script>
<input id="denivele_circuit" />
<div id="map_canvas"></div>