@xwei,
The innerHTML property allows reading and replacing everything within a given DOM element (HTML tag). In order to render a chart inside a div, you need to pass a unique id of div or DOM element of the div to CanvasJS.chart().
Using two div containers with a unique id and calling render method for the respective chart on the selected tab should work fine in your case. Please take a look at this JSFiddle. Also, refer this JSFiddle for an example on charts within Bootstrap tabs.
—-
Manoj Mohan
Team CanvasJS
