Howto: dynamically update markers with JSON on google maps
I am trying to update the location of a marker without refreshing the entire page. I tried to use setTimeout(function()
but I had no luck.
here is my code which I have so far.
early
function initialize() {
var mapOptions = {
center: new google.maps.LatLng(35.66, -80.50),
zoom: 8,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
var map = new google.maps.Map(document.getElementById("map-canvas"),
mapOptions);
var json = (function () {
var json = null;
$.ajax({
'async': false,
'global': false,
'url': "getjson.php",
'dataType': "json",
'success': function (data) {
json = data; } });
return json;})();
for (var i = 0, length = json.length; i < length; i++) {
var data = json[i],
latLng = new google.maps.LatLng(data.lat, data.lng);
var marker = new google.maps.Marker({
position: latLng,
map: map,
title: data.title
});
}
var infoWindow = new google.maps.InfoWindow();
google.maps.event.addListener(marker, "click", function(e) {
infoWindow.setContent(data.description);
infoWindow.open(map, marker);
});
(function(marker, data) {
google.maps.event.addListener(marker, "click", function(e) {
infoWindow.setContent(data.description);
infoWindow.open(map, marker);
});
})(marker, data);
}
google.maps.event.addDomListener(window, 'load', initialize);
here is my JSON output.
[{"lat":35.6606376,"lng":-80.5048653,"content":"bca"}, {"lat":42.6799504,"lng":-36.4949205,"content":"abc"}]
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2 answers
I would suggest using setInterval rather than setTimeout.
Here's some code that simulates updating via JSON in a fiddle using the JSON you provided with the "description" member added for each marker:
var map = null;
var gmarkers = [];
var intervalNumber = 0;
setInterval(function () {
new Request.JSON({
url: '/echo/json/',
data: {
json: JSON.encode([{
"lat": 35.6606376 + (0.01 * intervalNumber),
"lng": -80.5048653 + (0.1 * intervalNumber),
"content": "bca",
"description":"first marker"
}, {
"lat": 42.6799504 + (0.01 * intervalNumber),
"lng": -36.4949205 - (0.1 * intervalNumber),
"content": "abc",
"description": "second marker"
}]),
delay: 3
},
onSuccess: function (response) {
update_map(response);
intervalNumber++;
}
}).send();
}, 5000);
update_map = function (data) {
var bounds = new google.maps.LatLngBounds();
// delete all existing markers first
for (var i = 0; i < gmarkers.length; i++) {
gmarkers[i].setMap(null);
}
gmarkers = [];
// add new markers from the JSON data
for (var i = 0, length = data.length; i < length; i++) {
latLng = new google.maps.LatLng(data[i].lat, data[i].lng);
bounds.extend(latLng);
var marker = new google.maps.Marker({
position: latLng,
map: map,
title: data[i].title
});
var infoWindow = new google.maps.InfoWindow();
google.maps.event.addListener(marker, "click", function (e) {
infoWindow.setContent(data.description+"<br>"+marker.getPosition().toUrlValue(6));
infoWindow.open(map, marker);
});
(function (marker, data) {
google.maps.event.addListener(marker, "click", function (e) {
infoWindow.setContent(data.description+"<br>"+marker.getPosition().toUrlValue(6));
infoWindow.open(map, marker);
});
})(marker, data[i]);
gmarkers.push(marker);
}
// zoom the map to show all the markers, may not be desirable.
map.fitBounds(bounds);
};
function initialize() {
// initialize the map on page load.
var mapOptions = {
center: new google.maps.LatLng(35.66, -80.50),
zoom: 8,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
map = new google.maps.Map(document.getElementById("map-canvas"),
mapOptions);
// add the markers to the map if they have been loaded already.
if (gmarkers.length > 0) {
for (var i = 0; i < gmarkers.length; i++) {
gmarkers[i].setMap(map);
}
}
}
google.maps.event.addDomListener(window, 'load', initialize);
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https://developers.google.com/maps/documentation/javascript/reference
markerObject.setPosition(latlng:LatLng|LatLngLiteral)
I don't think you need to redraw the map, but just in case:
google.maps.event.trigger(mapObject, 'resize');
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