How to provide information to canDeactivate in Aurelia view-model -

i using candeactivate() in view-model. there way user navigate away view candeactivate should not checks , return true (in case, when user presses button in view). appears candeactivate not take arguments (such params passed router.navigatetoroute). if did, indicate button pressed in params arg when calling navigatetoroute. way give candeactivate needed piece of information?

starting in aurelia-router 1.4.0, candeactivate passed argument contains information need accomplish this