classy

This library helps you to handle assigning style that relies on multiple combinations of props or conditionals.

What problem do we want to solve here?

Let's suppose you have some good old conditional classes to be applied to an element:

<Button className={ `my-button ${ disabled ? 'is-disabled' : '' }` }>
	My Cool Button
</Button>

You could write:

import { classy } from '@welingtonms/classy';

<Button
	className={ classy( 'my-button', {
		'is-disabled': disabled,
	} ) }
>
	My Cool Button
</Button>;

Or, let's say you have a React component with props such as colorScheme, variant, validationStatus, disabled, and so on.

If you dare to style your component conditionally according to these props, you would have to write something like:

  import clsx from 'clsx'

  const { colorScheme, variant, validationStatus, disabled } = props

  <Button
    className={clsx({
      'some class combination a': colorScheme == 'dark' && variant == 'primary',
      'some class combination b': (colorScheme == 'light' || colorScheme == 'dark') && variant == 'secondary' && validationStatus == 'valid',
      'some class combination c': colorScheme == 'dark' || variant == 'terciary',
      'some class combination d': !disabled
    })}
  >
    My Cool Button
  </Button>

Well, what if you could write something like:

  import useClassy from '@welingtonms/classy'

  const { prop, classy } = useClassy(props)
  const { disabled } = props

  <Button
    className={classy({
      'some class combination a': prop({ colorScheme:'dark', variant == 'primary' }),
      'some class combination b': prop({ colorScheme: ['light', 'dark'], variant: 'secondary', validationStatus: 'valid' }),
      'some class combination c': prop([{ colorScheme: 'dark' }, { variant: 'terciary' }],
      'some class combination d': !disabled, // or prop({ disabled: false })
    })}
  >
    My Cool Button
  </Button>

Cool, huh?!

Or if you were using some CSS-in-JS library like styled-components, you would have something like:

import styled from 'styled-components';

const Button = styled.button`
	background: ${ ( { variant, scheme } ) => ( {
		'$button-primary-background': variant == 'primary',
		'$button-secondary-background':
			variant == 'secondary' && scheme == 'light',
		'$button-secondary-dark-background':
			variant == 'secondary' && scheme == 'dark',
		'$button-terciary-background': variant == 'terciary',
	} ) };

	border-color: ${ ( { variant, scheme } ) => ( {
		'$button-primary-border-color': variant == 'primary',
		'$button-secondary-border-color':
			variant == 'secondary' && scheme == 'light',
		'$button-secondary-dark-border-color':
			variant == 'secondary' && scheme == 'dark',
		'$button-terciary-border-color': variant == 'terciary',
	} ) };

	color: ${ ( { variant, scheme } ) => ( {
		'$button-primary-color': variant == 'primary',
		'$button-secondary-color': variant == 'secondary' && scheme == 'light',
		'$button-secondary-dark-color':
			variant == 'secondary' && scheme == 'dark',
		'$button-terciary-color': variant == 'terciary',
	} ) };
`;

Well, what about something simpler like:

import { classier, prop } from '@welingtonms/classy';

const Button = styled.button`
	background: ${ classier( {
		'$button-primary-background': prop( { variant: 'primary' } ),
		'$button-secondary-background': prop( {
			variant: 'secondary',
			scheme: 'light',
		} ),
		'$button-secondary-dark-background': prop( {
			variant: 'secondary',
			scheme: 'dark',
		} ),
		'$button-terciary-background': prop( { variant: 'terciary' } ),
	} ) };

	border-color: ${ classier( {
		'$button-primary-border-color': prop( { variant: 'primary' } ),
		'$button-secondary-border-color': prop( {
			variant: 'secondary',
			scheme: 'light',
		} ),
		'$button-secondary-dark-border-color': prop( {
			variant: 'secondary',
			scheme: 'dark',
		} ),
		'$button-terciary-border-color': prop( { variant: 'terciary' } ),
	} ) };

	color: ${ classier( {
		'$button-primary-color': prop( { variant: 'primary' } ),
		'$button-secondary-color': prop( {
			variant: 'secondary',
			scheme: 'light',
		} ),
		'$button-secondary-dark-color': prop( {
			variant: 'secondary',
			scheme: 'dark',
		} ),
		'$button-terciary-color': prop( { variant: 'terciary' } ),
	} ) };
`;

classy gives you more power to represent conditionals and helps you declutter your styling, making it more purposeful.