Utility Props (x.*)

Building complex components using utility props.

Traditionally when you use Emotion or styled-components, you write CSS, as object or as string but it is still CSS:

❌ Using a traditional approach where custom designs require custom CSS

const Container = styled.div`
  display: flex;
  max-width: 24rem;
  margin: 0 auto;
  padding: 1.5rem;
  border-radius: 0.5rem;
  background-color: #fff;
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
`
 const LogoWrapper = styled.div`
  flex-shrink: 0;
`
 const Logo = styled.img`
  height: 3rem;
  width: 3rem;
`
 const Content = styled.div`
  margin-left: 1.5rem;
  padding-top: 0.25rem;
`
 const Title = styled.h4`
  color: #1a202c;
  font-size: 1.25rem;
  line-height: 1.25;
`
 const Message = styled.p`
  color: #718096;
  font-size: 1rem;
  line-height: 1.5;
`
 function ChatNotification() {
  return (
    <Container>
      <LogoWrapper>
        <Logo src="/img/logo.svg" alt="ChitChat Logo" />
      </LogoWrapper>
      <Content>
        <Title>ChitChat</Title>
        <Message>You have a new message!</Message>
      </Content>
    </Container>
  )
}

With xstyled, you style components only using props:

✅ Using xstyled to build custom design without writing CSS

function ChatNotification() {
  return (
    <x.div
      p={6}
      maxWidth="sm"
      mx="auto"
      bg="white"
      borderRadius="xl"
      boxShadow="md"
      display="flex"
      alignItems="center"
      spaceX={4}
    >
      <x.div flexShrink={0}>
        <x.img h={12} w={12} src="/img/logo.svg" alt="ChitChat Logo" />
      </x.div>
      <x.div>
        <x.h4 fontSize="xl" fontWeight="medium" color="black">
          ChitChat
        </x.h4>
        <x.p color="gray-500">You have a new message!</x.p>
      </x.div>
    </x.div>
  )
}

This approach allows us to implement a completely custom component design without writing a single line of custom CSS.

You could find it ugly and complex, you are right. It could be confusing the first time you see it. But before throwing it, you should give a try!

They are several benefits from this approach:

• No intermediate components — Everything is built-in the component
• Fully declarative — Everything is declarative, a custom set of props give a custom rendering
• Concise — In a few line of code, you have a ready-to-use component

Why not inline styles?

By seeing this approach you may wonder why not using just inline styles. xstyled is close to inline style but it has several advantages over them:

• Designing with constraints — Using inline styles, every value is a magic number. xstyled uses values the design system defined in your theme.
• Responsive design — Unfortunately, media queries are not supported in inline styles. xstyled provides responsive variants to build responsive interface.
• Hover, focus, and other states — Inline styles can't target states like hover or focus, but xstyled state props make it easy to style those.

Why not css props?

If you know Emotion css prop, you could wonder why using xstyled instead of emotion css prop. There is several reasons:

• Designing with constraints — Theme is part of xstyled, you just have to type the name of a color to use it. It is not the case with CSS prop.
• Developer experience — Typing CSS is verbose and takes time. xstyled has short syntax for responsive, states, short prop names... Everything makes it easier than writing CSS.
• Utilities — xstyled is not just CSS, it has powerful utilities for spacing, gradients, transforms, grids...

Design Tokens

It exists several kind of design tokens:

• Global tokens: the primitive, for example #f43f5e
• Alias tokens: the alias of the primitive, for example red-500
• Logic tokens: the logic alias, for example cta-background-color

In built-in theme, we expose some alias tokens, for color red-500 is the alias of #f43f5e.

If you want to create a scaling design system, we recommend adding logic tokens in your theme. xstyled's th utility allows you to create design token aliases in your theme:

import { th, defaultTheme } from '@xstyled/...'

const theme = {
  ...defaultTheme
  colors: {
    ...defaultTheme,
    'cta-background-color': th.color('red-500'),
  }
}