labelFontWeight: String

Sets the font weight of label (text) shown in Range Buttons.

Default: “normal”
Options: “lighter”, “normal”, “bold”, “bolder” 
var stockChart = new CanvasJS.StockChart("container",
{
 .
 .
 rangeSelector: {
   buttonStyle: {
     labelFontWeight: "bolder",
     .
     .
   }
 },
 .
 . 
});
stockChart.render();
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