A brief history

Once upon a time, the Web was really simple and CSS didn’t even exist. We laid out pages using tables and frames. Good times.

Then CSS came to life, and after some time it became clear that frameworks could greatly help especially in building grids and layouts, Bootstrap and Foundation playing a big part of this.

Preprocessors like SASS and others helped a lot to slow down the frameworks adoption, and to better organize the code conventions like BEM and SMACSS grew in their usage, especially within teams.

Conventions are not a solution to everything, and they are complex to remember, so in the last few years with the increasing adoption of JavaScript and build processes in every frontend project, CSS got its way into JavaScript (CSS-in-JS).

New tools explored new ways of doing CSS-in-JS and a few succeeded with increasing popularity:

  • React Style
  • jsxstyle
  • Radium

and more.

Introducing Styled Components

One of the most popular of these tools is Styled Components.

It is the meant to be a successor of CSS Modules, a way to write CSS that’s scoped to a single component, and not leak to any other element in the page.

(more on CSS modules here and here)

Styled Components allow you to write plain CSS in your components without worrying about class names collisions.

Installation

Simply install styled-components using npm or yarn:

npm install styled-components
yarn add styled-components

That’s it! Now all you have to do is to add this import:

import styled from "styled-components";

Your first styled component

With the styled object imported, you can now start creating Styled Components. Here’s the first one:

const Button = styled.button`
  font-size: 1.5em;
  background-color: black;
  color: white;
`;

Button is now a React Component in all its greatness.

We created it using a function of the styled object, called button in this case, and passing some CSS properties in a template literal.

Now this component can be rendered in our container using the normal React syntax:

render(
  <Button />
)

Styled Components offer other functions you can use to create other components, not just button, like section, h1, input and many others.

The syntax used, with the backtick, might be weird at first, but it’s called Tagged Templates, it’s plain JavaScript and it’s a way to pass an argument to the function.

Using props to customize components

When you pass some props to a Styled Component, it will pass them down to the DOM node mounted.

For example here’s how we pass the placeholder and type props to an input component:

const Input = styled.input`
  //...
`;

render(
  <div>
    <Input placeholder="..." type="text" />
  </div>
);

This will do just what you think, inserting those props as HTML attributes.

Props instead of just being blindly passed down to the DOM can also be used to customize a component based on the prop value. Here’s an example:

const Button = styled.button`
  background: ${props => props.primary ? 'black' : 'white'};
  color: ${props => props.primary ? 'white' : 'black'};
`;

render(
  <div>
    <Button>A normal button</Button>
    <Button>A normal button</Button>
    <Button primary>The primary button</Button>
  </div>
);

Setting the primary prop changes the color of the button.

Extending an existing Styled Component

If you have one component and you want to create a similar one, just styled slightly differently, you can use extend:

const Button = styled.button`
  color: black;
  //...
`;

const WhiteButton = Button.extend`
  color: white;
`;

render(
  <div>
    <Button>A black button, like all buttons</Button>
    <WhiteButton>A white button</WhiteButton>
  </div>
);

It’s Regular CSS

In Styled Components, you can use the CSS you already know and love. It’s just plain CSS. It is not pseudo CSS nor inline CSS with its limitations.

You can use media queries, nesting and everything you might come up with.

Using Vendor Prefixes

Styled Components automatically add all the vendor prefixes needed, so you don’t need to worry about this problem.

Conclusion

That’s it for this Styled Components introduction! These concepts will help you get an understanding on the concept and help you get up and running with this way of using CSS in JavaScript.