TechradarDev/radar/2021-07-01/css-in-js.md

title, ring, quadrant, tags

title	ring	quadrant	tags
CSS-in-JS	trial	methods-and-patterns	frontend

CSS-in-JS is a method where JavaScript is used to style components. The first libraries which implemented this technique were Styled-Components, Emotion & JSS.

Example:

const Button = styled.button`
  display: inline-block;
  padding: 0.5rem 0;
  background: transparent;
  color: white;
  border: 2px solid white;

  ${(props) =>
    props.primary &&
    css`
      background: white;
      color: black;
    `}
`;

return <Button primary>Click me</Button>;

Advantages of CSS-in-JS

• Local scoping instead of global namespace
• No classname to element mapping
• Use the full power of JavaScript to enhance CSS (loops, variables & more)
• Dynamic styling & theming (access to state or props)
• TypeScript support

Disadvantages of CSS-in-JS

• Runtime cost when using dynamic styling
• Slightly different syntax than traditional CSS (object syntax vs template literals)
• Can add an extra layer of complexity

In the meantime CSS-in-JS has evolved even more. There are some libraries which leverages nearly zero-runtime costs such as Stitches or Vanilla Extract while still providing an excellent developer experience with TypeScript.

We at AOE think that CSS-in-JS is the future of writing good, performant and maintainable CSS, therefore we already use different CSS-in-JS solutions throughout multiple applications.