This example shows how do control the overlay charts using java script.

overlay 1 overlay 2

<applet code=com.objectplanet.chart.BarChartApplet
 archive=chart.jar width=300 height=200 name=BarChart VIEWASTEXT>
<param name=sampleValues value="20,10,40,30,50">
<param name=overlay0 value="line">
<param name=overlay0_sampleValues value="20,10,40,30,50">
<param name=overlay0_sampleColors value="red">
<param name=overlay1 value="line">
<param name=overlay1_sampleValues value="10,5,20,15,25">
<param name=overlay1_sampleColors value="blue">
<param name=overlay1_stackedOn value=true>
</applet>

<form name="input">
overlay 1 <INPUT NAME="overlay1" type=checkbox checked onClick=repaint()>
overlay 2 <INPUT NAME="overlay2" type=checkbox checked onClick=repaint()>
</form>

<script LANGUAGE="JavaScript">
<!--
function repaint() {
   document.BarChart.chart.setOverlayChartOn(0, document.input.overlay1.checked);
   document.BarChart.chart.setOverlayChartOn(1, document.input.overlay2.checked);
}
//-->
</script>