valueFormatString: String

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

var  chart =  new  CanvasJS.Chart("container",
   crosshair: {
	enabled: true,
	valueFormatString: "#,##0.##",

Please refer Format Number and Format Date-Time for list of valueFormatString options available.
Try it Yourself by Editing the Code below.

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