there are multiple packages. some of them are only for development and some of them are needed in production too. for example think of eslint, a package for code quallity, in this package you do not need it in your production build, and only for developlemnt. but a package like chart.js is needed in your production build too. so you need to decide that if a package is needed in your production build or not. if its not needed you can add with

npm install --save-dev 

the above code will only add the package in your development and wont bundle it with your production build

hope that helps