Making ring buffers (donuts) in Google Earth Engine

Question

I am trying to generate multiple buffers around a layer that represents cities (FeatureCollection). Use the following code to create the buffers: // Function to create buffers of different sizes in Google Earth Engine . The problem is that this code generates polygons that include the inside area. I need to generate buffers on the outside, like doughnuts or perimeter rings.

I tried to use .difference to remove the original polygons from the buffers but I get the error "....difference is not a function"

Can anyone help me?

var geometry = 
    /* color: #d63000 */
    /* displayProperties: [
      {
        "type": "rectangle"
      },
      {
        "type": "rectangle"
      },
      {
        "type": "rectangle"
      }
    ] */
    ee.FeatureCollection(
        [ee.Feature(
            ee.Geometry.Polygon(
                [[[-92.93044076036253, 43.38666530027385],
                  [-92.93044076036253, 43.371630789523294],
                  [-92.90812478135862, 43.371630789523294],
                  [-92.90812478135862, 43.38666530027385]]], null, false),
            {
              "system:index": "0"
            }),
        ee.Feature(
            ee.Geometry.Polygon(
                [[[-93.016614771593, 43.389328699363205],
                  [-93.016614771593, 43.36986507859759],
                  [-92.99155221055784, 43.36986507859759],
                  [-92.99155221055784, 43.389328699363205]]], null, false),
            {
              "system:index": "1"
            }),
        ee.Feature(
            ee.Geometry.Polygon(
                [[[-93.09137330125608, 43.39935439198635],
                  [-93.09137330125608, 43.38213974024519],
                  [-93.06734070848265, 43.38213974024519],
                  [-93.06734070848265, 43.39935439198635]]], null, false),
            {
              "system:index": "2"
            })]);

var RingBuffer = function (Poligono, DistBuff) {
  
var BufferFeature = function(f) {
  f = ee.Feature(f);
  var buffer_size = f.get('buffer_size');
  return f.buffer(buffer_size);   
};

var BufferFeaturesByDistance = function (fc, buffer_size) {

var SetBufferSize = function(f) {
    return f.set({'buffer_size': buffer_size});
  };

return (Poligono).map(SetBufferSize).map(BufferFeature);
};

var Buffer = BufferFeaturesByDistance(Poligono, DistBuff)

return (Buffer).difference(Poligono)
};

var Buff1 = RingBuffer (geometry, 2000);

Map.addLayer(Buff1);

Answer 1

Here is a simple example on how to do a donut buffer:

var point = ee.Geometry.Point(-90.1751, 18.5854)
var donut = point.buffer(5000).difference(point.buffer(3000))

Map.centerObject(point, 12)
Map.addLayer(point)
Map.addLayer(donut)