# Developer guide

Vue Styleguidist created from React Styleguidist, implement additional support to read and compile .vue files.

Styleguidist isn’t an ordinary single-page app and some design decisions may look confusing to an outsider. In this guide, we’ll explain these decisions to un-confuse potential contributors.

The main thing is that we’re running two apps at the same time: user’s components and Styleguidist UI. They share a Webpack configuration and have styles in the same scope (there’s only one scope in CSS). And we can control only one of these two apps: Styleguidist UI. That puts us under some restrictions:

  • Our styles should not affect user component styles.
  • User styles (especially global like Bootstrap) should not affect Styleguidist UI.
  • body styles (like font-family) should affect user components as the user expects but not Styleguidist UI.

# How it works

Vue Styleguidist uses vue-docgen-api to parse source files (not transpiled). vue-docgen-api finds exported Vue components and generates documentation.

Styleguidist uses Markdown for documentation: each JavaScript code block is rendered as an interactive playground with CodeMirror. To do that we extract all these code blocks using Remark.

Webpack loaders (see below) generate JavaScript modules. In each of these modules, each component specified by the user is parsed with their documentation and examples. The whole module is then passed to a React app which renders the style guide.

# Webpack loaders and Webpack configuration

We use Webpack loaders to hot reload the style guide on changes in user components, styles, and Markdown documentation. We have three loaders (loaders folder):

  • styleguide-loader: loads components and sections;
  • vuedoc-loader: loads props documentation using vue-docgen-api;
  • examples-loader: loads examples from Markdown files;

There are two more loaders — css-loader and styles-loader. They are one-line aliases to corresponding Webpack loaders. We don’t want to rely on a Webpack loader resolver because its behavior can be changed by the user’s Webpack config (Create React App does that for example). This way we can bypass Webpack resolver and use Node resolver instead. These loaders are used like this:

require('!!../../../loaders/style-loader!../../../loaders/css-loader!codemirror/lib/codemirror.css')

!! prefix tells Webpack not to use any other loaders that may be listed in a Webpack configuration to load this module. This ensures that the user’s Webpack configuration won’t affect Styleguidist.

Styleguidist tries to load and reuse a user’s Webpack config (webpack.config.js in the project root folder). It works most of the time but has some restrictions: Styleguidist ignores some fields and plugins because they are already included (like webpack.HotModuleReplacementPlugin), don’t make sense for a style guide (like output) or may break Styleguidist (like entry).

We’re trying to keep Styleguidist’s own Webpack config minimal to reduce clashes with user’s configuration.

# React components

Most of StyleGuidist UI components consist of two parts: Foo/Foo.js that contains all logic and Foo/FooRenderer.js that contains all markup and styles. This allows users to customize rendering by overriding *Renderer component using webpack aliases (or styleguideComponents config option):

// styleguide.config.js
const path = require('path')
module.exports = {
  webpackConfig: {
    resolve: {
      alias: {
        'rsg-components/Wrapper': path.join(
          __dirname,
          'lib/styleguide/Wrapper'
        )
      }
    }
  }
}

All Styleguidist components should be imported like this: import Foo from 'rsg-components/Foo' to make aliases work.

Each component folder usually has several files:

  • Foo/Foo.js (optional for litteral components);
  • Foo/FooRenderer.js;
  • Foo/Foo.spec.js — tests;
  • Foo/index.js — reexport of Foo.js or FooRenderer.js.

# Styles

For styles we use JSS, it allows users to customize their style guide and allows us to ensure styles isolations (thanks to jss-plugin-isolate). No user styles should affect Styleguidist UI and no Styleguidist styles should affect user components.

Use classnames to merge several class names or for conditional class names, import it as cx (import cx from 'classnames').

We use Styled higher-order component to allow theming (see theme and style style guide config options). Use it like this:

import React from 'react'
import Styled from 'rsg-components/Styled'

export const styles = ({ fontFamily, fontSize, color }) => ({
  button: {
    fontSize: fontSize.base,
    fontFamily: fontFamily.base,
    color: color.light,
    '&:hover, &:active': {
      isolate: false,
      color: color.lightest
    }
  }
})

export function ExamplePlaceholderRenderer({ classes }) {
  return (
    <button className={classes.button}>I am a styled button</button>
  )
}

Check available theme variables in src/styles/theme.js.

Because of isolation and theme, you need to explicitly declare fontFamily, fontSize and color. Add isolate: false to your hover styles, otherwise, you’ll have to repeat base non-hover styles.

# Render vue components

To render vue components, styleguidist uses the Preview.js React component.

As soon as users open the page, Preview is mounted.

The function rendering examples when codemirror updates is executeCode().

# Separate script from template

First, we extract any JavaScript from it by doing this:

  • if it contains new Vue return the contents as a script
  • if it is a single file component extract template and script and compile the script
  • else look at the first line that starts with a < then everything that is before it is js and the rest will be HTML

# Prepare code

The scripts are transformed from es6 or jsx to es5 using buble. The names of the variables that are declared in the global scope are extracted since they cannot be used in an eval. The code is then wrapped in a getConfig function.

# Render example

First, make sure that the mount point is ready and save it in a variable Second prepare the component by executing the function created above exampleComponent() And finally instantiate vue to mount our made up component in the mounting point

# Hot Reload

To enable hot reloading even when the site is compiled, we need to keep the root of the Preview component unchanged. We instead will play with whatever is inside this root. At unmount, when the Preview component is Reloaded, we clear the vue instance to place a new one: unmountPreview().