valueFormatString: String

Defines how values must be formatted before they appear in Crosshair Label.

var  chart =  new  CanvasJS.Chart("container",
{
 .
 .
 axisY:{
   crosshair: {
	enabled: true,
	valueFormatString: "#,##0.##",
	.
	.
   }
 },
 .
 . 
});
chart.render();