Using vanilla CSS in React application

Yet another way to apply CSS styles in JavaScript. It's not using an inline styling though. It's injecting a <style> tag.

import React from 'react';
import CSSX from 'react-cssx';

class Component extends React.Component {
  render() {
    return (
      <CSSX styles={ this.css() }>
        <h1>Title styled with <i>CSSX</i></h1>
      </CSSX>
    );
  }
  css() {
    var color = '#BADA55';

    return (
      <style>
        h1 {
          color: {{ color }};
        }
        h1 i {
          text-decoration: underline;
        }
      </style>
    );
  }
}

To make the code above works you'll need:

CSSX component (npm install react-cssx)
CSSX transpiler (It's available here. Get it as a webpack loader, Meteor package or gulp plugin.)

Demo here and here.

CSSX component

<CSSX> component has only one required attribute - styles. It should be an array in the following format:

[
  ['h1', { 'font-size': '32px' }],
  ['h1 small', { 'font-size': '24px', 'font-weight': 'bold' }]
]

Of course writing CSS that way is not really nice. So let's use CSSX and replace it with:

css() {
  return (
    <style>
      h1 {
        font-size: 32px;
      }
      h1 small {
        font-size: 24px;
        font-weight: bold;
      }
    </style>
  );
}

Notice that we should use a function that returns a <style> tag. If we create the <style> tag directly (in the render method for example) we'll get the CSS applied straight away to the whole page.

CSSX component's wrapper

The <CSSX> component generates a <div> by default. Use the data-element attribute to specify the tag that you need:

<CSSX styles={ ... } data-element='h1'>
  <p>Paragraph</p>
</CSSX>

Scoping

If you check some of the examples in a browser you'll see that the created styles are scoped to a specific element. For example:

class Component extends React.Component {
  render() {
    return (
      <section>
        <p>First paragraph</p>
        <CSSX styles={ this.styleParagraph('#F00', 'second') }>
          <p>Second paragraph</p>
        </CSSX>
        <CSSX styles={ this.styleParagraph('#00F', 'third') }>
          <p>Third paragraph</p>
        </CSSX>
      </section>
    );
  }
  styleParagraph(color, text) {
    return (
      <style>
        p {
          color: {{ color }};
        }
        p::before {
          content: {{ text }};
        }
      </style>
    );
  }
}

There are three paragraphs rendered on the screen:

CSSX

The first one does not have any local styles attached. However, the second and the third one are styled differently. They have their own dedicated CSS. CSSX library creates two <style> tags in the <head> of the document.

CSSX

Misc

If this sounds interesting to you follow the links below:

krasimir / react-cssx

readme

Using vanilla CSS in React application

CSSX component

CSSX component's wrapper

Scoping

Misc