Jon's Programming Blog

Using NPM as a Build Tool

I really like simplicity. The tools I use, I like them to make my life easy, not hard. They need to work out of the box. No huge configuration settings, just make it easy so I can get to work.

Well, along come grunt, gulp, and now even more tools since I first started writing this that I won’t mention. Two build tools for JavaScript. Wonderful, we need tools to help us build our files. Wait a minute. We already have a build tool, it’s called NPM. By the time I started learning JavaScript, gulp.js was the cool thing. I think gulpl.js is a really nice tool. But, if you are building simple apps or even complex apps you can get away with just the command line and keep things simple and concise.

So, if you really want to learn how to use NPM as your build tool there’s a well written tutorial called How to Use npm as a Build Tool which you can read.

So, some gripes people have about using NPM as a command tool are that you can’t comment your scripts and that you can’t write variables. Well, enter YAML. I haven’t done variables in YAML but you can write them. You can also comment in YAML. You can even write variables in your command line. So, I write my scripts in YAML and merge that into my package.json file.

Here’s my scripts in YAML.

# scripts run with npm. to build to package.json
# in command line in directory `.../mobiledlr/dist`
# `node ./tasks/buildPackage`

  # bring together api.yml file with d.ts definitions
  # print to public
  api: |
    cpx "../ts/api/**" api
    && node ./tasks/api-generator.js    
  browserify: browserify
  deploy: node ./tasks/deploy.js

  # dsr app
  dsr: |
    browserify ./views/dealer_service_report/dsr.js
    | uglifyjs -m -c
    | tee ./public/js/dsr.min.js
    | ngzip
    > ./public/js/dsr.min.js.gz    
  r: ramda
  start: node ./app.js --use_strict

  # Copy convert stylus files in directory to css
  # files in public directory.
  stylus: stylus -w -c ../static/stylus -o public/css
  test: node ./tasks/tests.js
  typescript: |
    -m commonjs
    -t es5
    --outDir ./
    --rootDir ../ts    

  watch: nodemon ./app.js --use_strict

  # this has been deprecated in preference for browserify
  webpack: |
        ./node_modules/.bin/webpack -w --cache --config ./config/webpack.config.js

  # e.g., npm run watchify ./dsr.js -o ./public/dsr.js
  watchify: watchify

And here is the code I use to merge it with my package.json file:

import r = require('ramda')
import yaml = require('js-yaml')
import {readFile, writeFile} from 'fs'

var npmPackage = require('../package.json')

readFile('../scripts.yml', 'utf-8', (err, file) => {
    if (err) {
        console.log('Error reading scripts.yml', err)
        return process.exit(1)

    scripts = yaml.load(file),
    combined = r.merge(npmPackage, scripts)

    writeFile('./package.json', JSON.stringify(combined, null, '  ').replace(/\\n/g, ' '), err => {
        if (err) {
            console.error('There was an error writing to package.json!', err)
            return process.exit(1)

I put the scripts script in a directory called tasks and just use the command line node ./tasks/scriptsPackage anytime I change my scripts.yml file. I suppose I could make it a CLI compatible command. But I haven’t needed to. But I’m sure I would eventually want to. Once I do that I could add it to my scripts.yml file! Only the first time I call it would I need to call it directly, so it would be something like this: node ./.node_modules/.bin/scripts ../ts/scripts.yml.

JavaScript-Style Promises in F# On-the-Fly Lambda Expressions in JavaScript