17

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 script (like the one below), and install them automatically, instead of installing them manually, one-by-one (using npm).

#!/usr/bin/env node

var DNode = require('dnode');
var sys = require('sys');
var fs = require('fs');
var http = require('http');

var html = fs.readFileSync(__dirname + '/web.html');
var js = require('dnode/web').source();

//the rest of this script is omitted.
Anderson Green
  • 30,230
  • 67
  • 195
  • 328
  • 1
    Possible duplicate of [Possible to install all missing modules for a node application?](http://stackoverflow.com/questions/13189239/possible-to-install-all-missing-modules-for-a-node-application) – Anderson Green Sep 10 '16 at 01:17

4 Answers4

19

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

Aminadav Glickshtein
  • 23,232
  • 12
  • 77
  • 117
Andrew Mao
  • 35,740
  • 23
  • 143
  • 224
  • 2
    Is there any way to generate a list of dependencies for a script that doesn't have a `package.json` file associated with it? That's what I'm really trying to find out here, since I'm just working with a single file. – Anderson Green Jan 09 '13 at 00:13
  • I hope it would be feasible to generate a `package.json` file for a module that doesn't yet have a `package.json` file associated with it. – Anderson Green Jan 09 '13 at 00:22
  • 1
    If you're going to the trouble of requiring all the modules at the beginning of the script, why not just record those in your package file as well? Are you going after some automagical way to parse and fetch the dependencies of your script during execution? `package.json` is also useful because you can specify the versions of your dependencies, and make sure things don't break when your script is run in the future. – Andrew Mao Jan 09 '13 at 00:22
  • Yes, I'm going after some way to fetch the dependencies of the script during execution. It might be possible to do this by running the script over and over, and then installing each of the needed packages based on the console output, for example: `Error: Cannot find module 'progress'` – Anderson Green Jan 09 '13 at 00:26
  • Also, I'm not sure which part of the docs I should refer to. What would I need to do to create a `package.json` file that simply specifies a list of dependencies for a script? – Anderson Green Jan 09 '13 at 00:52
  • See here: https://npmjs.org/doc/json.html. For an example, this page seems to be decent: http://blog.nodejitsu.com/package-dependencies-done-right, or the `package.json` for npm itself: https://github.com/isaacs/npm/blob/master/package.json – Andrew Mao Jan 09 '13 at 00:58
  • Great Mate. Time Saving. – kta Sep 08 '15 at 03:08
  • The link in answer seems invalid, Here's another page https://docs.npmjs.com/getting-started/using-a-package.json – yu yang Jian Sep 09 '17 at 04:50
  • By the way, try `yarn`, sometimes it works much faster than `npm` (and sometimes it's buggy) – Aminadav Glickshtein Sep 25 '17 at 07:41
6

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)
          }
        }
      })
    }
  }
})()
Gust van de Wal
  • 5,211
  • 1
  • 24
  • 48
Aminadav Glickshtein
  • 23,232
  • 12
  • 77
  • 117
0

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()
Gust van de Wal
  • 5,211
  • 1
  • 24
  • 48
0

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);
    }
};
user3210615
  • 7
  • 1
  • 18
  • This is hardly an answer on its own. The only difference between yours and mine are the few characters afters `npm install`. You could have simply commented or - if what you added is an improvement in every aspect possible - changed my answer. – Gust van de Wal Oct 03 '20 at 15:42