fontWeight: String

Set the Font Weight of ToolTip Content.

Default: “normal”
Example: “lighter”, “normal”, “bold” , “bolder”

var  chart =  new  CanvasJS.Chart("container",
    fontWeight: "bold",

Try it Yourself by Editing the Code below.

  Also See:    

In order to provide better support, we have closed the comments and switched completely to our Forums.
If you have any questions, please feel free to ask in our forums.