Buffer Components

A shared set of UI Components using React and CSS Modules.

Demo: https://bufferapp.github.io/buffer-components/

To use this in your project start at the usage section. If you'd like to add to this library skip to component development.

Usage

Install the package and save the exact version:

npm install @bufferapp/components -SE

Now in your code you can import a specific component:

import Button from '@bufferapp/components/Button';

Requirements

For the component library you're required to use a few plugins and a valid Webpack config.

First, you'll need React installed (0.14 or newer):

npm i react react-dom -SE

In addition to your Babel configuration (not documented), you'll need the style-loader Webpack plugin:

npm i style-loader -SDE

Your Webpack config should use the proper config, here is an example:

module.exports = {
  module: {
    loaders: [
      {
        test: /\.css$/,
        loaders: [
          'style-loader',
        ],
      },
    ],
  },
};

Component Development

• Quick Start
• Test
• Component Anatomy
• FAQ

Quick Start

Install Node Modules

npm i

Start React Storybook

npm start

Open http://localhost:9001

Test

Run Linter And Test

npm run test

Run Test and watch for changes

npm run test-watch

Update Test Snapshots

npm run test-update

Note: only commit these if you have manually inspected them with a story

Component Anatomy

src/ # root
+-- MyComponent/ # component root
  `-- index.js # component display logic
  `-- story.js # storybook entry

Versioning

major.minor.patch

Considered patch release

Can upgrade without changes to the codebase

• Add a component
• Add a new prop to a component

Considered minor release

An upgrade would require a code change to work

• Remove a component
• Remove a prop

Considered major release

• Major milestone achieved (i.e a complete set of components)
• Complete re-skinning of components
• Up for debate

FAQ

What is a component

In the current implementation components are all functional and stateless.

This means that UI is a function of state since we're using pure functions to build our views.

UI = f(state)

How do I determine the scope of a component

This is a tough question, it really depends. But as a general rule, a component should be simple enough to be reusable across multiple applications and be not much longer than 150 lines of code. This is a good one to seek advice if you're not sure.

What's the development workflow look like?

Note: this is a way to do this, but not necessarily the way to build components. For this workflow let's create a component called NewComponent.

1. Create a branch with the name of the new component

Note: also make sure you're up to date

git checkout master
git pull -r
git checkout -b task/add-newcomponent

2. Install dependencies and start the storybook

npm i && npm start

open http://localhost:9001 in your browser

3. Create a NewComponent folder under src (see Component Anatomy)

src/
+-- NewComponent/

4. Create a story for the NewComponent

src/
+-- NewComponent/
 `-- story.js

populate story.js with a default story

// story.js
import React from 'react';
import { storiesOf } from '@storybook/react';
import NewComponent from './index';

storiesOf('Card', module)
  .add('Default', () => (
    <NewComponent />
  ));

Now when you look at Storybook you should see a broken story (red screen)

5. Implement your component

src/
+-- NewComponent/
 `-- story.js
 `-- index.js

populate index.js with the new component

import React from 'react';
import { calculateStyles } from '../lib/utils';

const NewComponent = ({ hovered }) =>
  <div
    style={calculateStyles({
      default:{
        background: 'green',
      },
      hovered: {
        background: 'red',
      }
    },{
      hovered, // key matches above style key and is activated when value is true
    })}
  >
    NewComponent
  </div>;

export default NewComponent;

6. Run the test for the first time

It's important to note that this creates a snapshot of the component. All tests ran in the future will be tested against this snapshot to ensure they haven't changed.

npm t

7. Commit it!

git add .
git commit -m "Add NewComponent"
git push -u origin task/add-newcomponent

At this point it's a good idea to generate a PR on github :)

How do I write tests for a component?

This automatically happens when you write stories. They are tested with jest snapshots under the hood.

Since components are functional and stateless we can use snapshot testing to get complete coverage.

You're verifying that each property change has the expected outcome in HTML.

The first time the test is run it generates a new snapshot. The second time it's checked against the snapshot.

How Do I Update A Snapshot

npm run test-update

How do determine what a component does?

There's a pattern you can follow

1. Look at the Component.propTypes section

• This is essentially the API of the component

2. Look at the render function
3. Look at any helper functions
4. Ask one of the contributors :)