Npm postinstall only on development

问题:

I have npm module with following package.json

{
  "name": "my-app",
  "version": "0.0.0",
  "scripts": {
    "prepublish": "bower install",
    "build": "gulp"
  },
  "dependencies": {
    "express": "~4.0.0",
    "body-parser": "~1.0.1"
  },
  "devDependencies": {
   "gulp": "~3.6.0",
   "bower": "~1.3.2"
  }
}

When I deploy my app to production I don't want install devDependecies so, I run npm install --production. But in this case prepublish script are called, but it doesn't need, because I use CDN links in production.

How to call postinstall script only after npm install but not after npm install --production?

回答1:

Newer npm (& Yarn) versions include support for the prepare script that is run after each install run but only in development mode. Also, the prepublish is deprecated. This should be enough:

{
  scripts: {
    "prepare": "bower install"
  }
}

Docs: https://docs.npmjs.com/misc/scripts

回答2:

I think you cannot choose what scripts are run based on the --production argument. What you can do, however, is supply a script which tests the NODE_ENV variable and only runs bower install if it's not "production".

If you are always in a unix-y environment, you can do it like this:

{ 
  scripts: {
    "prepublish": "[ \"$NODE_ENV\" != production ] && bower install"
  }
}

回答3:

This only works if you're on a unix-like environment:

NPM sets an environment variable to "true" when install is run with --production. To only run the postinstall script if npm install was not run with --production, use the following code.

"postinstall": "if [ -z \"$npm_config_production\" ]; then node_modules/gulp/bin/gulp.js first-run; fi",

回答4:

I work with windows, osx and linux so I use a NON environment specific solution to solve this problem:

In the postinstall handler i execute a js script that checks process.env.NODE_ENV variable and does the work.

in my specific case I have to execute a gulp task only in development env:

part of package.json

"scripts": {
  "postinstall": "node postinstall"
}

all postinstall.js script

if (process.env.NODE_ENV === 'development') {
  const gulp = require('./gulpfile');
  gulp.start('taskname');
}

last row of gulpfile.js

module.exports = gulp;

it's important to export gulp from the gulpfile.js because all tasks are in that specific gulp instance.

回答5:

Solution that is less dependent on unix nature of your shell:

  "scripts": {
    "postinstall": "node -e \"process.env.NODE_ENV != 'production' && process.exit(1)\" || echo do dev stuff"
  },

回答6:

I'm using if-env module. It's less verbose.

PS: I didn't test it on windows yet.

Install with:

npm i if-env

than in package.json scripts:

"postinstall-production": "echo \"production, skipping...\"",
"postinstall-dev": "echo \"doing dev exclusive stuff\"",
"postinstall": "if-env NODE_ENV=production && npm run postinstall-production || npm run postinstall-dev"

回答7:

Landed here because I had the same issue. Ended up with a solution that tests for the existence of a package under node_modules that I know should only be available in development.

{
  "scripts": {
    "postinstall": "bash -c '[ -d ./node_modules/@types ] && lerna run prepare || echo No postinstall without type info'" 
  }
}

This works fine for me conceptually, as the prepare scripts here called by lerna are mainly to ts-to-js compilations.

回答8:

I have a more general problem - where I want to skip running the postinstall script on local (direct) installs - like when I'm developing the package and run yarn add --dev my-new-dependency.

This is what I came up with. It works with both npm and yarn.

postinstall.js:

const env = process.env;
if (
    // if INIT_CWD (yarn/npm install invocation path) and PWD
    // are the same, then local (dev) install/add is taking place
    env.INIT_CWD === env.PWD ||
    // local (dev) yarn install may have been run
    // from a project subfolder
    env.INIT_CWD.indexOf(env.PWD) === 0
) {
    console.info('Skipping `postinstall` script on local installs');
}
else {
    // do post-installation things
    // ...
}

package.json:

"script": {
    "postinstall": "node postinstall.js",
    ...