NPM preinstall script

Question

I am trying to run some policing script before any packages are installed. For Example:

{
  "name": "pre-hook-check",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "preinstall": "echo preinstall",
    "postinstall": "echo postinstall"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "abc": "^0.6.1",
    "preact": "^8.2.5"
  }
}

It seems the pre and post install script on above example only works when I do npm install, but I want that to run every time I try to install anything.

For example: Let's say I want to write a script to check for the version of the package any time my team runs npm install <some package>. I want to check for the version of installing package and verify that it's version is above "1.0.0" else don't let them install.

I was planning to write a preinstall script that goes

npm info lodash version

and checks for the version of any package I am trying to install. If the version is not available, I plan to make it interactive and ask user's acknowledgement before install.

Answer 1

You are right the preinstall script runs only when we do npm install and there is currently no way to run a script before installing a module but you can use shell scripting and npm view https://docs.npmjs.com/cli/view to do so .

First , create a moduleinstall.sh file which has the same scope as your package.json and the below shell script to it

echo 'Enter the name of the module'
read module_name
npm view $module_name version 
echo "Do you want to install this version(y/N) " 
read option 
if [ "$option" = "N" ] || [ "$option" = "n" ]
then 
echo "exiting...."
exit 1
else
npm install $module_name
fi

make sure you make it executable using chmod +x moduleinstall.sh and then write this in your package.json

"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"info": "./moduleinstall.sh"
}

Now you just have to run the command npm run info and then follow the instruction to install a module by checking the version . You can advance it using different options of npm view and shell scripting. Hope this helps.