[Update]
You can achieve stacked line chart with the help of stacked area chart by setting fillOpacity: 0. Please take a look at this jsfiddle.
himanshu,
You can achieve stacked line chart with the help of stacked area chart by customizing it with color: "transparent" and using lineColor, markerColor and toolTipContent properties based on your requirement. Please take a look at this jsfiddle.
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Priyanka M S
Team CanvasJS
