Is it possible to install npm package only if it has not been already installed?

Question

Is it possible to install npm package only if it has not been already installed?

I need this to speed up test on CircleCI, but when I run npm inst

Answer 1

with bash you can do

[ $(node -p "require('protractor/package.json').version") != "2.1.0" ] && npm install protractor@2.1.0