borderThickness: Number

Sets the thickness of border around the Title in pixels. To display border around title, set the borderThickness to a number greater than zero.

• It is recommended to add padding whenever borderThickness is set so that border is not too close to the text.

var  chart =  new  CanvasJS.Chart("container",
{
 .
 .
 title:{
  borderThickness: 2,
 },
 .
 .
});
chart.render();