Is it possible to automatically install the required modules for a node.js script?

Question

Is it possible to automatically download the required modules for a node.js script? I\'m wondering if it\'s possible to generate a list of required modules for a node.js scr

Answer 1

I was inspired by @Aminadav Glickshtein's answer to create a script of my own that would synchronously install the needed modules, because his answer lacks these capabilities.

I needed some help, so I started an SO question here. You can read about how this script works there.
The result is as follows:

const cp = require('child_process')

const req = async module => {
  try {
    require.resolve(module)
  } catch (e) {
    console.log(`Could not resolve "${module}"\nInstalling`)
    cp.execSync(`npm install ${module}`)
    await setImmediate(() => {})
    console.log(`"${module}" has been installed`)
  }
  console.log(`Requiring "${module}"`)
  try {
    return require(module)
  } catch (e) {
    console.log(`Could not include "${module}". Restart the script`)
    process.exit(1)
  }
}

const main = async () => {
  const http    = await req('http')
  const path    = await req('path')
  const fs      = await req('fs')
  const express = await req('express')

  // The rest of the app's code goes here
}

main()

And a one-liner (139 characters!). It doesn't globally define child_modules, has no last try-catch and doesn't log anything in the console:

const req=async m=>{let r=require;try{r.resolve(m)}catch(e){r('child_process').execSync('npm i '+m);await setImmediate(()=>{})}return r(m)}

const main = async () => {
  const http    = await req('http')
  const path    = await req('path')
  const fs      = await req('fs')
  const express = await req('express')

  // The rest of the app's code goes here
}

main()

Answer 2

Yes, there is a great piece of code called NPM for exactly this: https://npmjs.org/

You specify dependent packages in a package.json file (see the docs for syntax) and you can use npm install . to pull them in all at once, and then require them from your script.

Package.json syntax page: https://docs.npmjs.com/getting-started/using-a-package.json

The first time you install a module, your can provide any number of modules to install, and add the --save argument to automatically add it to your package.json

npm i --save dnode request bluebird

The next time, someone will execute npm i it will automatically install all the modules specified in your package.json

Answer 3

when I open the script on windows by right clicking then open with nodejs it tries to install the node modules in system32 and it fails

I modified the script and it works

oneliner:

var req=async m=>{let r=require;try{r.resolve(m)}catch(e){console.log('Installing ' + m);r('child_process').execSync('npm i --prefix "'+__dirname+'" ' +m);await setImmediate(()=>{})}return r(m)};

full:

var cp = require('child_process');
var req = async module => {
    try {
        require.resolve(module);
    } catch (e) {
        console.log(`Could not resolve "${module}"\nInstalling`);
        cp.execSync(`npm install --prefix "${__dirname}" ${module}`);
        await setImmediate(() => {});
        console.log(`"${module}" has been installed`);
    }
    console.log(`Requiring "${module}"`);
    try {
        return require(module);
    } catch (e) {
        console.log(`Could not include "${module}". Restart the script`);
        process.exit(1);
    }
};

Answer 4

I have written a script for this.
Place it at the start of your script, and any uninstalled modules will be installed when you run it.

(function () {
  var r = require
  require = function (n) {
    try {
      return r(n)
    } catch (e) {
      console.log(`Module "${n}" was not found and will be installed`)
      r('child_process').exec(`npm i ${n}`, function (err, body) {
        if (err) {
          console.log(`Module "${n}" could not be installed. Try again or install manually`)
          console.log(body)
          exit(1)
        } else {
          console.log(`Module "${n}" was installed. Will try to require again`)
          try{
            return r(n)
          } catch (e) {
            console.log(`Module "${n}" could not be required. Please restart the app`)
            console.log(e)
            exit(1)
          }
        }
      })
    }
  }
})()