Open source library of React components from the YouVersion Bible.com team


4091.1.4-alpha.36 months ago4 years agoMinified + gzip package size for @youversion/melos in KB


Melos: The YouVersion React Component Library


This project sets the standard for user interfaces on various YouVersion web projects, containing many of the pieces that come together to create a clean, simple and engaging user experience on Bible.com.


Example components in a mobile view


If you want to start using these components right away, here's a brief intro and a couple examples. You can see all of the available components, and examples with usage, in our Storybook for this library.

If you're looking to develop or add to this collection of components, see the Development section of this document.

Getting Started

  1. Install these components for use, by running
npm install @youversion/melos
  1. Import the component you want to use...
import Card from '@youversion/melos'
  1. Use the Component somewhere!
        Contents in a card component!

For usage examples of each of the components in this library, see our Storybook.

Test Drive all Components in a Sandbox Environment with React Storybook

Example Storybook Animation

We've built React Storybook into our repo. This allows us to create a centrally located sandbox where developers can discover new components and test drive them using different prop combinations before using them in their projects.

To see the complete collection of components, code examples, and test-drive them live, see our Storybook.

Available Components

See the complete list of available components, and test drive them all in our Storybook.

Our components are organized into categories, based on their normal usage patterns. This hopefully makes them easier to find and utilize here and in the Storybook.

Standardized Typography

Components for body copy, captions, headings (1 - 3), titles and links. By using these components throughout our projects, we create a standard for typography that adheres to our style guide.

Example of default typography styles.

Convenient Layouts

These components are useful when designing layouts. They provide simple components for creating complex or frequently used layout patterns (such as 'vertical layouts evenly spaced' or 'fixed left and right content with a centered title')

Links and Buttons

Standardized way of displaying, links, buttons, icon/image buttons, etc.

Example default button styles


Set of third-party and internal logos in SVG format, wrapped as React components with props for height, width and fill.


Collection of icons currently being used in our web apps, in SVG format, wrapped as React components with props for height, width and fill.

Media Queries

Standard set of media query breakpoints and pre-defined ranges for small, medium, large and x-large screens. They're defined in Javascript for use with our dynamically generated CSS (via Glamor and Glamorous).


Standard components for handling form input. Inputs, Selects, Textareas and a Debounced higher order component.


Currently, just a simple Card component for wrapping UI elements in a card.

Utility Functions

A handy set of utility functions that we use in multiple places to make calculations or parse data such as converting arrays to object, fast searching/filtering long lists in the browser, darken/lighten hex colors by percent, monitor scroll position, monitor browser width, and more.

CSS, Themes, and Dynamically Generated CSS using Glamor and Glamorous

Each component fully encapsulates all of the HTML, CSS and Javascript that it needs to exist. No need for external CSS, LESS or SASS files. Glamorous generates dynamic class names on the fly and inserts the resulting CSS rules into the <head>. This makes our page payloads much more efficient, requiring a user to download only the exact amount of CSS required to render the components within the page.

Our Default Themes

All of our components have a default theme that we use in our own web apps and websites, such as Bible.com. Our themes are broken down into two areas.

  • Style Constants : a Javascript object which defines all of the font weights, colors, margin, padding, line heights, etc. that will be used by our components
  constants: {
    fontFamily: {
      primary: '"proxima-nova",ArialMT,"Helvetica Neue",Arial,"Liberation Sans",FreeSans,sans-serif',
    fontWeight: {
      normal: 400,
      semibold: 600,
      bold: 700
    color: {
      text: 'black',
      muted: '#777777',
      primary: '#6AB750',
      light: 'white'
    radius: {
      medium: 4
    border: {
      thin: 'solid 1px #ddd'
    fontSize: {
      xsmall: 10,
      small: 12,
      default: 16,
      medium: 18,
      large: 24,
      xlarge: 30
    lineHeight: {
      medium: '24px'
    letterSpacing: {
      xsmall: 2
    padding: {
      none: 0,
      medium: 12
    margin: {
      none: 0
  • Component Style Map Functions : a function for each component that maps which style constants get applied to which style properties on a component. The functions have two arguments: theme and props. theme contains value of the constants key in your theme object, merged with the default constants. props is an object containing the props passed into your component. Here's an example:
  Heading1: (theme, props) => {
    const { muted } = props
    return {
      fontFamily: theme.fontFamily.primary,
      fontWeight: theme.fontWeight.bold,
      fontSize: theme.fontSize.xlarge,
      color: muted ? theme.color.muted : theme.color.text,
      padding: theme.padding.none,
      margin: theme.margin.none

Putting it Together in a Custom Theme

You can mix and match any combination of style constants and style-mapping functions to create a custom theme. You only have to supply the parts that you actually want to override. For example, you can just change one thing, like this:

const customTheme = {
  constants: {
    fontFamily: {
      primary: 'AppleGothic'

Or, you can replace more, with something like this:

const customTheme2 = {
  constants: {
    fontFamily: {
      primary: 'Avenir Next'
    color: {
      text: 'olivegreen',
      muted: 'darkyellow',
      primary: '#483D8B',
      light: 'white'
    fontSize: {
      medium: 16
  ButtonMajor: (theme) => {
    return {
      fontSize: theme.fontSize.xlarge

Applying Your Theme to components

First, import our <Theme /> component:

import Theme from '@youversion/melos/dist/components/themes/Theme'

Then, define a variable containing your custom theme, like this:

const customTheme = {
  constants: {
    fontFamily: {
      primary: 'AppleGothic'

Next, set definition prop on the <Theme/> component to your custom theme like this:

<Theme definition={customTheme}></Theme>

Place components inside the <Theme /> component to have your custom theme applied to them:

<Theme definition={customTheme}>
    <VerticalSpace space={15}>
      <Heading1>Heading One</Heading1>
      <Heading1 muted>Heading One</Heading1>
      <Heading2>Heading Two</Heading2>
      <Heading2 muted>Heading Two</Heading2>
      <Heading3>Heading Three</Heading3>
      <Heading3 muted>Heading Three</Heading3>
      <Body muted>Body</Body>
      <Caption1>Caption One</Caption1>
      <Caption1 muted>Caption One</Caption1>
      <Caption2>Caption Two</Caption2>
      <Caption2 muted>Caption Two</Caption2>
      <Title muted>Title</Title>
      <LinkText href="https://www.bible.com">Link Text</LinkText>
      <ButtonMajor>Button Major</ButtonMajor>

Under the Hood

Under the hood we're using Glamorous to generate <style> blocks inside <head>. You can read the Glamorous docs for Themes to get a more information about what's actually happening.


Before starting, please refer to our Contribution Guidelines.

Using Storybook to develop these components

We recommend the use of React Storybook for developing these components.

  1. Dependencies! In the project root, run npm install.

  2. Start the server:

     $ npm run storybook
  3. Open browser to http://localhost:8080/.

  4. Develop components in their respective folders (/src/components/{component-name}/).

  5. Write stories for your components in their respective stories folder. E.g., /src/components/{component-name}/stories/{name}.stories.js.

  6. Write tests for your component in their respective __tests__ folder. E.g., /src/components/{component-name}/__tests__/{name}.unit.test.js.

For more information on Storybook specifically, see the Storybook site.

Run Tests

npm run test

Generate a Production Build

npm run compile

Watch for Code Changes and Automatically Rebuild During Development

npm run watch


Please check out our Contribution Guidelines for detailed information on how you can lend a hand.


Apache License 2.0

How did you come up with the name mélos?

In the Bible, 1 Corinthians 12:12 says...

“For just as the body is one and has many members [ mélos ], and all the members of the body, though many, are one body, so it is with Christ.”

"mélos" is the Greek word translated as "members" or "parts" in this verse.

We liked the idea of many parts (or mélos) working together to build something bigger. That's the way the Church is being built, and that's also the way good web applications are built - each of the mélos doing the work it was designed for.

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.