PSS lang

Prop-based StyleSheets aims to improve styling syntax for React.js projects.

button.Button {
  // `props.theme.white`
  color: $theme.white;

  &:hover {
    color: red;
  }

  &:isSelected {
    // `color` set to `props.isSelectedColor` when `props.isSelected` is true
    color: $isSelectedColor;
  }
}

This repository only includes a parser that generates an AST when given PSS syntax.

💅 Use it with styled-components

Why?

If you want to apply prop-based styles to your React components so far, you either need to:

• write CSS classes, then manually map them to each one of our component props
  if prop.isSelected, add 'is-selected' CSS class
• use expressions (with css-in-js) inside style literals
  ${props => props.isSelected ? 'blue' : 'red'}

Now, think about it: do you have any additional logic for mapping our element to hover styles only when it'll be hovered? We don't, because we already acknowledge that writing :hover makes it conditionally styled, based on our element's state.

The idea here is similar: making props part of that state, right inside our style declaration.

Parser Output Example

Here's the generated output for the example code above:

StyleElement {
  selector: StyleSelector {
    type: 'originalTag',
    name: 'Button',
    options: { isExtension: true, extendFrom: 'button' }
  },
  styles: [
    StyleProperty {
      property: 'color',
      value: StylePropertyValue { type: 'computed', value: 'theme.white' }
    },
    StyleElement {
      selector: StyleSelector { type: 'raw', name: '&:hover' },
      styles: [
        StyleProperty {
          property: 'color',
          value: StylePropertyValue { type: 'raw', value: 'red' }
        }
      ]
    },
    StyleElement {
      selector: StyleSelector {
        type: 'conditional',
        name: 'props.isSelected',
        value: { leftHand: 'props.isSelected' }
      },
      styles: [
        StyleProperty {
          property: 'color',
          value: StylePropertyValue { type: 'computed', value: 'isSelectedColor' }
        }
      ]
    }
  ]
}

null and empty properties have been omitted

License

eveningkid @ MIT