[javascript] Resize Google Maps marker icon image

When I load an image into the icon property of a marker it displays with its original size, which is a lot bigger than it should be.

I want to resize to the standard to a smaller size. What is the best way to do this?

Code:

function addMyPos(latitude,longitude){
  position = new google.maps.LatLng(latitude,longitude)
  marker = new google.maps.Marker({
    position: position,
    map: map,
    icon: "../res/sit_marron.png"
  });
}

So I just had this same issue, but a little different. I already had the icon as an object as Philippe Boissonneault suggests, but I was using an SVG image.

What solved it for me was:
Switch from an SVG image to a PNG and following Catherine Nyo on having an image that is double the size of what you will use.

Delete origin and anchor will be more regular picture

  var icon = {
        url: "image path", // url
        scaledSize: new google.maps.Size(50, 50), // size
    };

 marker = new google.maps.Marker({
  position: new google.maps.LatLng(lat, long),
  map: map,
  icon: icon
 });

A complete beginner like myself to the topic may find it harder to implement one of these answers than, if within your control, to resize the image yourself with an online editor or a photo editor like Photoshop.

A 500x500 image will appear larger on the map than a 50x50 image.

No programming required.

MarkerImage has been deprecated for Icon

Until version 3.10 of the Google Maps JavaScript API, complex icons were defined as MarkerImage objects. The Icon object literal was added in 3.10, and replaces MarkerImage from version 3.11 onwards. Icon object literals support the same parameters as MarkerImage, allowing you to easily convert a MarkerImage to an Icon by removing the constructor, wrapping the previous parameters in {}'s, and adding the names of each parameter.

Phillippe's code would now be:

 var icon = {
     url: "../res/sit_marron.png", // url
     scaledSize: new google.maps.Size(width, height), // size
     origin: new google.maps.Point(0,0), // origin
     anchor: new google.maps.Point(anchor_left, anchor_top) // anchor 
 };

 position = new google.maps.LatLng(latitud,longitud)
 marker = new google.maps.Marker({
  position: position,
  map: map,
  icon: icon
 });

If you are using vue2-google-maps like me, the code to set the size looks like this:

<gmap-marker
  ..
  :icon="{
    ..
    anchor: { x: iconSize, y: iconSize },
    scaledSize: { height: iconSize, width: iconSize },
  }"
>

As mentionned in comments, this is the updated solution in favor of Icon object with documentation.

Use Icon object

var icon = {
    url: "../res/sit_marron.png", // url
    scaledSize: new google.maps.Size(50, 50), // scaled size
    origin: new google.maps.Point(0,0), // origin
    anchor: new google.maps.Point(0, 0) // anchor
};

 posicion = new google.maps.LatLng(latitud,longitud)
 marker = new google.maps.Marker({
  position: posicion,
  map: map,
  icon: icon
 });