Yeoman generator for starting ES6 npm module with Mocha, Istanbul, Travis, Karma


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40Jul 1, 2016Mar 25, 2016Minified + gzip package size for @clef/generator-es6-npm-module in KB



This generator creates an npm-compatible module with support for ES6, Webpack (building), Mocha (testing), Chai (assertion), Karma (test running), and TravisCI (continuous integration).

Out of the box, you'll get green tests with coverage and helpful NPM scripts for versioning and publishing.

Getting Started

npm install -g yo @clef/generator-es6-npm-module
mkdir my-project && cd my-project
yo @clef/es6-npm-module

Or you can create folder with your project and just copy\paste this code to terminal (you should be located under your project folder)

npm install -g yo @clef/generator-es6-npm-module && yo @clef/es6-npm-module

Project structure

When project is generated you will get project with that structure:

|-- my-project
  |-- src
  |  |-- index.js
  |-- spec
  |  |-- my-project.spec.js
  |-- .babelrc
  |-- .editorconfig
  |-- .gitignore
  |-- .npmignore
  |-- .travis.yml
  |-- karma.conf.js
  |-- package.json
  |-- webpack.config.js
  |-- README.md

Common questions

How do I develop two packages at once?

npm provides good tooling for developing many packages at once. You're likely in the following situation:

  • You have package-b which depends on package-b
  • You'd like to work on them at the same time

To achieve this, we will npm link package-b into the global space and then link it back into package-a. Follow these steps:

cd /path/to/package-b
npm link
cd /path/to/package-a
npm link package-b

You can read more about npm link here.

When do I add to "dependencies" vs. a "peerDependencies"?

Because our build system uses both Webpack and Browserify, we can run into issues where dependencies are built into our distributed source twice. This is very bad. To address this, we use peerDependencies extensively.

  • peerDependencies - any module that is shared by one or more of our components should be added to peerDependencies. If you add a module to peerDependencies, you should also add it to devDependencies, so that it will be installed for testing and development (peerDependencies are not installed by default in npm > 3).
  • dependencies - any module that only this component relies on should be added to dependencies.

This is a pain in the butt and we are working on a solution.

Known issues

Duplicate module import

This issue crops up in the following situation:

  • We have two packages package-a and package-b which both depend on react (or another module)
  • We npm link package-a into package-b
  • We try build package-a with browserify

It will manifest as this error:

Uncaught Invariant Violation: addComponentAsRefTo(...): Only a ReactOwner can have refs. You might be adding a ref to a component that was not created inside a component's `render` method, or you have multiple copies of React loaded (details: https://fb.me/react-refs-must-have-owner).

In this situation, react will be loaded twice in the browserify bundle.

To fix this, follow the steps outlined here.

cd /path/to/project-b
cd node_modules/react
npm link
cd /path/to/project-a
npm link react

This issue only affects packages when thay are connected using npm link.

If you find any bugs or have a feature request, please open an issue on github!

The npm package download data comes from npm's download counts api and package details come from npms.io.