Hide the chart's series in ExtJs 4 - extjs

Question

I'm migrating ExtJs 3 application to ExtJs 4. One of the component that I need to change is a chart that has series of bars and lines on it. It displays the data for previous and current years. Beside the chart there is a checkbox "Compare to previous year". When it checked all line series should be visible and hidden when it is not checked.
In ExtJs 3 I did this task by setting visibility:hidden for series styles this way: chart.setSeriesStyles(...). But in ExtJs 4 this function is absent and I can't find any other way to hide series on demand.
Here is the code of my chart:
var store = Ext.create('Ext.data.Store', {
fields: [
'month','data1','data2','data3','prev_data1','prev_data2','prev_data3'
],
proxy: {
type: 'ajax',
url: '/getmonthlystats.php'
}
});
this.statChart = Ext.create('Ext.chart.Chart', {
flex: 1,
store: store,
axes: [{
type: 'Numeric',
position: 'left',
minimum: 0,
maximum: 100,
fields: [
'data1',
'data2',
'data3',
'prev_data1',
'prev_data2',
'prev_data3'
],
label: {
renderer: Ext.util.Format.numberRenderer('0,0')
},
grid: true
},{
type: 'Category',
position: 'bottom',
fields: ['month'],
label: {
rotate: {
degrees: 315
}
}
}],
series: [{
type: 'column',
yField: ['data1','data2','data3'],
xField: 'month'
},
{
type: 'line',
yField: 'prev_data1',
xField: 'month'
},{
type: 'line',
yField: 'prev_data2',
xField: 'month'
},{
type: 'line',
yField: 'prev_data3',
xField: 'month'
}]
});
So, the lines prev_data1, prev_data2, prev_data3 should be shown or hidden when needed (depending on the checkbox state). Does anyone know the way to do that?
Thanx.

Answer 1

Try this (sample from my code):
handler: function (checkbox, checked) {
if (checked)
chart.series.getAt(index).showAll();
else
chart.series.getAt(index).hideAll();
}

Answer 2

For ExtJS 4.2.x
If you use 'legend' with your charts, this code will be better for you:
var chart = Ext.getCmp(chartId);
var series = chart.series.getAt(seriesIndex);
if (value) {
series.showInLegend = true;
series.showAll();
} else {
series.showInLegend = false;
series.hideAll();
}
chart.redraw();