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The Google Maps JavaScript program can respond to various events generated by the user. This chapter provides examples demonstrating how to perform event handling while working with Google Maps.
Adding an Event Listener
You can add an event listener using the method addListener(). It accepts parameters such as object name on which we want to add the listener, name of the event, and the handler event.
Example
The following example shows how to add an event listener to a marker object. The program raises the zoom value of the map by 5 each time we double-click on the marker.
<!DOCTYPE html>
<html>
<head>
<script src = "https://maps.googleapis.com/maps/api/js"></script>
<script>
var myCenter = new google.maps.LatLng(17.433053, 78.412172);
function loadMap(){
var mapProp = {
center: myCenter,
zoom:5,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
var map = new google.maps.Map(document.getElementById("googleMap"),mapProp);
var marker = new google.maps.Marker({
position: myCenter,
title:''Click to zoom''
});
marker.setMap(map);
//Zoom to 7 when clicked on marker
google.maps.event.addListener(marker,''click'',function() {
map.setZoom(9);
map.setCenter(marker.getPosition());
});
}
</script>
</head>
<body onload = "loadMap()">
<div id = "googleMap" style = "width:580px; height:400px;"></div>
</body>
</html>
It produces the following output −
Opening an Info Window on Click
The following code opens an info window on clicking the marker −
<!DOCTYPE html>
<html>
<head>
<script src = "https://maps.googleapis.com/maps/api/js"></script>
<script>
var myCenter = new google.maps.LatLng(17.433053, 78.412172);
function loadMap(){
var mapProp = {
center:myCenter,
zoom:4,
mapTypeId:google.maps.MapTypeId.ROADMAP
};
var map = new google.maps.Map(document.getElementById("googleMap"),mapProp);
var marker = new google.maps.Marker({
position:myCenter,
});
marker.setMap(map);
var infowindow = new google.maps.InfoWindow({
content:"Hi"
});
google.maps.event.addListener(marker, ''click'', function() {
infowindow.open(map,marker);
});
}
</script>
</head>
<body onload = "loadMap()">
<div id = "googleMap" style = "width:580px; height:400px;"></div>
</body>
</html>
It produces the following output −
Removing the Listener
You can remove an existing listener using the method removeListener(). This method accepts the listener object, therefore we have to assign the listener to a variable and pass it to this method.
Example
The following code shows how to remove a listener −
<!DOCTYPE html>
<html>
<head>
<script src = "https://maps.googleapis.com/maps/api/js"></script>
<script>
var myCenter = new google.maps.LatLng(17.433053, 78.412172);
function loadMap(){
var mapProp = {
center:myCenter,
zoom:4,
mapTypeId:google.maps.MapTypeId.ROADMAP
};
var map = new google.maps.Map(document.getElementById("googleMap"),mapProp);
var marker = new google.maps.Marker({
position:myCenter,
});
marker.setMap(map);
var infowindow = new google.maps.InfoWindow({
content:"Hi"
});
var myListener = google.maps.event.addListener(marker, ''click'', function() {
infowindow.open(map,marker);
});
google.maps.event.removeListener(myListener);
}
</script>
</head>
<body onload = "loadMap()">
<div id = "googleMap" style = "width:580px; height:400px;"></div>
</body>
</html>
It produces the following output −
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