SOURCE

function Food(options) {
  options = options || {};
  this.x = options.x || 0;
  this.y = options.y || 0;
  this.width = options.width || 20;
  this.height = options.height || 20;
  this.color = options.color || 'green';
}
var position = 'absolute';
Food.prototype.render = function (map) {
  var div = document.createElement('div');
  map.appendChild(div);
  div.style.left = this.x + 'px';
  div.style.top = this.y + 'px';
  div.style.position = position;
  div.style.width = this.width + 'px';
  div.style.height = this.height + 'px';
  div.style.backgroundColor = this.color;
}
var map = document.getElementById('map');
var food = new Food();
food.render(map);

<div id="map"></div>

#map {
  width: 300px;
  height: 200px;
  background-color: lightgray;
  position: relative;
}