Answer by cherankrish for What's the difference between dependencies, devDependencies and peerDependencies in npm package.json file?

In short

1. Dependencies - npm install <package> --save-prod installs packages required by your application in production environment.

2. DevDependencies - npm install <package> --save-dev installs packages required only for local development and testing

3. Just typing npm install installs all packages mentioned in the package.json

so if you are working on your local computer just type npm install and continue :)