how to get all markers on google-maps-v3

Is there a way to get all the markers on Google Maps?

If you mean "how can I get a reference to all markers on a given map" - then I think the answer is "Sorry, you have to do it yourself". I don't think there is any handy "maps.getMarkers()" type function: you have to keep your own references as the points are created:

var allMarkers = [];
....
// Create some markers
for(var i = 0; i < 10; i++) {
    var marker = new google.maps.Marker({...});
    allMarkers.push(marker);
}
...

Then you can loop over the allMarkers array to and do whatever you need to do.

The one way found is to use the geoXML3 library which is suitable for usage along with KML processor Version 3 of the Google Maps JavaScript API.

I'm assuming you have multiple markers that you wish to display on a google map.

The solution is two parts, one to create and populate an array containing all the details of the markers, then a second to loop through all entries in the array to create each marker.

Not know what environment you're using, it's a little difficult to provide specific help.

My best advice is to take a look at this article & accepted answer to understand the principals of creating a map with multiple markers: https://stackoverflow.com/questions/2870670/multiple-infowindows-tearing-my-hair-out

If you are using JQuery Google map plug-in then below code will work for you -

var markers = $('#map_canvas').gmap('get','markers');

For an specific cluster use: getMarkers() Gets the array of markers in the clusterer.

For all the markers in the map use: getTotalMarkers() Gets the array of markers in the clusterer.

Google Maps API v3:

I initialized Google Map and added markers to it. Later, I wanted to retrieve all markers and did it simply by accessing the map property "markers".

var map = new GMaps({
    div: '#map',
    lat: 40.730610,
    lng: -73.935242,
});

var myMarkers = map.markers;

You can loop over it and access all Marker methods listed at [Google Maps Reference][1].

[1]: https://developers.google.com/maps/documentation/javascript/reference#Marker "Google Maps Reference"