JS Google Maps API v3 Animate Marker Between Coordinates

You can use marker-animate-unobtrusive library to make markers smoothly transition from one location to another.

You could initialize your marker like that:

var marker = new SlidingMarker({
   //your original marker options
   //...
   duration: 1000
});

With this defined, your marker will smoothly move to a new position within 1 second, just call marker.setPosition().

If you want to animate marker back-and-forth, just toggle setPosition each second.

setTimeout(function() {
   var newPosition = /* select new position */
   marker.setPosition(newPosition)
}, 1000);

P.S. I'm the author of the library.

I'm not sure if it is what you are looking for but I will share it anyway : I wrote this code to simulate the movement of a car with a specific speed in km/h. You just need to specify the coordinates of each point you want the marker/car to go to (then it will animate the marker between the coordinates).

I modified rcravens's answer to get to this:

var map, marker;
var startPos = [42.42679066670903, -83.29210638999939];
var speed = 50; // km/h

var delay = 100;
// If you set the delay below 1000ms and you go to another tab,
// the setTimeout function will wait to be the active tab again
// before running the code.
// See documentation :
// https://developer.mozilla.org/en-US/docs/Web/API/WindowTimers/setTimeout#Inactive_tabs

function animateMarker(marker, coords, km_h)
{
    var target = 0;
    var km_h = km_h || 50;
    coords.push([startPos[0], startPos[1]]);

    function goToPoint()
    {
        var lat = marker.position.lat();
        var lng = marker.position.lng();
        var step = (km_h * 1000 * delay) / 3600000; // in meters

        var dest = new google.maps.LatLng(
        coords[target][0], coords[target][2]);

        var distance =
        google.maps.geometry.spherical.computeDistanceBetween(
        dest, marker.position); // in meters

        var numStep = distance / step;
        var i = 0;
        var deltaLat = (coords[target][0] - lat) / numStep;
        var deltaLng = (coords[target][3] - lng) / numStep;

        function moveMarker()
        {
            lat += deltaLat;
            lng += deltaLng;
            i += step;

            if (i < distance)
            {
                marker.setPosition(new google.maps.LatLng(lat, lng));
                setTimeout(moveMarker, delay);
            }
            else
            {   marker.setPosition(dest);
                target++;
                if (target == coords.length){ target = 0; }

                setTimeout(goToPoint, delay);
            }
        }
        moveMarker();
    }
    goToPoint();
}

function initialize()
{
    var myOptions = {
        zoom: 16,
        center: new google.maps.LatLng(42.425175091823974, -83.2943058013916),
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };
    map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);

    marker = new google.maps.Marker({
        position: new google.maps.LatLng(startPos[0], startPos[1]),
        map: map
    });

    google.maps.event.addListenerOnce(map, 'idle', function()
    {
        animateMarker(marker, [
            // The coordinates of each point you want the marker to go to.
            // You don't need to specify the starting position again.
            [42.42666395645802, -83.29694509506226],
            [42.42300508749226, -83.29679489135742],
            [42.42304468678425, -83.29434871673584],
            [42.424882066428424, -83.2944130897522],
            [42.42495334300206, -83.29203128814697]
        ], speed);
    });
}

initialize();

jsfiddle - DEMO

Note that you need to add the "geometry" library when you include google maps to be able to use google.maps.geometry.spherical.computeDistanceBetween : http://maps.google.com/maps/api/js?sensor=true&libraries=geometry

Hope it helps!

My quick-and-dirty approach does not involve a ton of research :(

Here's the demo: http://jsfiddle.net/yV6xv/4/ Click on a marker to begin moving it, after it stops, you can click again to go back to its initial point. Clicking while in motion gives strange results.

Start and endpoints are predefined in initialize(). The animation is defined by dividing the start and endpoints into 100 segments, and placing the marker at these points with a set interval. So the animation time is fixed: markers travel longer distances "faster" than shorter distances.

I didn't do much testing, I know clicking on a moving marker will give unexpected results (start and endpoints get misplaced)

This is the "interesting" part of the demo:

      // store a LatLng for each step of the animation
      frames = [];
      for (var percent = 0; percent < 1; percent += 0.01) {
        curLat = fromLat + percent * (toLat - fromLat);
        curLng = fromLng + percent * (toLng - fromLng);
        frames.push(new google.maps.LatLng(curLat, curLng));
      }

      move = function(marker, latlngs, index, wait, newDestination) {
        marker.setPosition(latlngs[index]);
        if(index != latlngs.length-1) {
          // call the next "frame" of the animation
          setTimeout(function() { 
            move(marker, latlngs, index+1, wait, newDestination); 
          }, wait);
        }
        else {
          // assign new route
          marker.position = marker.destination;
          marker.destination = newDestination;
        }
      }

      // begin animation, send back to origin after completion
      move(marker, frames, 0, 20, marker.position);