Babel doesn't work, returns CLI errors

Question

I installed Babel locally in my project with the following command:

npm install babel-cli babel-core babel-preset-es2015 --save-dev

This gives me the following output in package.json:

{
  "name": "my_project",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "build": "babel src -d lib"
  },
  "scripts": {
    "build": "babel --presets es2015 src -d lib"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "babel": "^6.5.2",
    "babel-cli": "^6.18.0",
    "babel-core": "^6.18.2",
    "babel-loader": "^6.2.8",
    "babel-preset-es2015": "^6.18.0",
    "webpack": "^1.13.3"
  },
  "dependencies": {
    "lodash": "^4.17.2"
  }
}

I'm not sure, but it looks like it was installed successfully. But when I try to run npm run babel I get:

npm ERR! Darwin 15.3.0
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "run" "babel"
npm ERR! node v7.0.0
npm ERR! npm  v4.0.2

npm ERR! missing script: babel
npm ERR! 
npm ERR! If you need help, you may report this error at:
npm ERR!     <https://github.com/npm/npm/issues>

npm ERR! Please include the following file with any support request:
nam ERR!     /Path/To/My/Project/npm-debug.log

Why doesn't Babel work? In the package.json file it is included:

Answer 1

So you run npm run babel

and it said npm ERR! missing script: babel

may be you meant this: npm run build

---

Two things to ponder:

1. npm run

   This runs an arbitrary command from a package's "scripts" object.

2. babel is not a script in your package.json, but a transpiler for JavaScript which converts ES6 to ES5.

so if you run npm run build, that will execute the build command defined here:

  "scripts": {
    "build": "babel src -d lib"
  },

I also see there is a duplicate of scripts object.

Answer 2

There are different ways to run an installed npm executables.

The easiest way is to install it also globally. In your case you need only babel-cli to be available in command line. so npm install -g babel-cli will do.

If you want to install it only locally, babel executable is also available on node_modules/.bin/babel. But surely it's much of typing for a command.

The other way that you are trying is to use npm-run-scripts. In this case you have to define the script in your package.json. You already have a build script that you can run like npm run build. So for npm run babel you need the same form of script definition:

"scripts": {
    "build": "babel src -d lib",
    "babel": "babel script.js --out-file script-compiled.js" // For example
}
...

This is used mostly to have a shorthand for a command that you want to run frequently like a build script.

You can also provide additional arguments to an npm script with this syntax:

npm run babel -- --presets es2015

Notice the additional -- here.

There is still another option where you can install a package once globally and link to it from different projects:

npm install -g babel-cli and in your project direcotory npm link babel-cli.

The most common way is the easiest one where you install executable packages (command line interfaces) both globally and locally.