code: function getDistance(p1, p2, props) {
    if (!props) {
      props = PROPS_XY;
    }
    var x = p2[props[0]] - p1[props[0]];
    var y = p2[props[1]] - p1[props[1]];
  
    return Math.sqrt((x * x) + (y * y));
  }
docs: calculate the absolute distance between two points
  @param {Object} p1 {x, y}
  @param {Object} p2 {x, y}
  @param {Array} [props] containing x and y keys
  @return {Number} distance