code: function () {
  		var series = this,
  			pointAttr,
  			data = series.data,
  			chart = series.chart,
  			plotX,
  			plotY,
  			i,
  			point,
  			radius,
  			graphic;
  
  		if (series.options.marker.enabled) {
  			i = data.length;
  			while (i--) {
  				point = data[i];
  				plotX = point.plotX;
  				plotY = point.plotY;
  				graphic = point.graphic;
  
  				// only draw the point if y is defined
  				if (plotY !== UNDEFINED && !isNaN(plotY)) {
  
  					/* && removed this code because points stayed after zoom
  						point.plotX >= 0 && point.plotX <= chart.plotSizeX &&
  						point.plotY >= 0 && point.plotY <= chart.plotSizeY*/
  
  					// shortcuts
  					pointAttr = point.pointAttr[point.selected ? SELECT_STATE : NORMAL_STATE];
  					radius = pointAttr.r;
  
  					if (graphic) { // update
  						graphic.animate({
  							x: plotX,
  							y: plotY,
  							r: radius
  						});
  					} else {
  						point.graphic = chart.renderer.symbol(
  							pick(point.marker && point.marker.symbol, series.symbol),
  							plotX,
  							plotY,
  							radius
  						)
  						.attr(pointAttr)
  						.add(series.group);
  					}
  				}
  			}
  		}
  
  	}
docs: Draw the markers