Post script

Npm allows you to add "pre" or "post" scripts for any script, by having another script with a matching name and adding "pre" or "post" to the beginning of them.

Let's say you have a project structure with a subfolder, that you also would like to install when the user runs npm install, that can be solved with:

{
  "scripts": {
    "postinstall": "cd folder && npm i"
  }
}