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.

Solution

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.