Ionic cordova run android --prod not working properli

I have installed ion2-calendar in my ionic application using npm install ion2-calendar moment --save and i have made some changes on its files located in node_modules/ion2-calendar/dist/components/month.component.js, i have added (panEnd) and (panStart) in its dates.it is working good using ionic serve and ionic ocrdova run android.but the events are not working when we make build usinng --prod option like

ionic ocrdova run android --prod
the build was successfull and we can run the app on mobile,but the added event does not works.is there anything we need to do to add this changees in production build?