CEP.scss

CEP: Component, Element and Property, a methodology that help you styling single file component.

Installation

yarn add -D cep.scss

# or use npm

npm i -D cep.scss

And import it into the index scss file in your project.

@import 'cep.scss';

Usage / Core

The CEP provides a series of mixins and functions to help you writing stylesheet for components, these tools can auto generate specified selector blocks and convert different units.

• core mixin： comp(), elem(), prop(), when()
• core function: rem()

---

Namespace <ns>-*

The css class name prefix for components, controlled by global variable $namespace.

@import 'cep.scss';

// there is a ui library 'huiji-ui', its namespace is `hj`
$namespace: 'hj';
@import 'src/huiji-ui/button.scss';
@import 'src/huiji-ui/list.scss';
@import 'src/huiji-ui/card.scss';
@import 'src/huiji-ui/layout.scss';

// for the common service components, you can use `c` as their namespace.
$namespace: 'c';
@import 'src/components/header.scss';
@import 'src/components/footer.scss';
@import 'src/components/sidebar.scss';
@import 'src/components/navbar.scss';

// for the views components, you can use `v` as their namespace.
$namespace: 'v';
@import 'src/views/home.scss';
@import 'src/views/user.scss';
@import 'src/views/about.scss';
@import 'src/views/article.scss';

---

Component <ns>-<component>

A component has its own css class name.

<button class="hj-button"><!----></button>

@include comp('button') {
  // style for .hj-button
}

The mixin comp($name) will auto generate a selector at root:

• .hj-button.

---

Element <ns>-<component>_<element>

The CEP will combine the component name and the element name with single underline as css class name for elements.

<button class="hj-button">
  <i class="hj-button_icon"></i>
  <span class="hj-button_content">{{content}}</span>
</button>

@include comp('button') {
  // style for .hj-button

  @include elem('icon', 'content') {
    // shared style for the element icon and content
  }

  @include elem('icon') {
    // style for the element icon
  }

  @include elem('content') {
    // style for the element content
  }
}

The mixin elem($name-list...) will auto generate selectors:

• .hj-button .hj-button_icon, .hj-button .hj-button_content
• .hj-button .hj-button_icon
• .hj-button .hj-button_content.

Note: don't nest elements block in scss if not necessary.

---

Property <ns>p-<name>_<value>

For a component, control style by properties of the component, use namespace with a letter 'p' as prefix, combine the property name and the value with single underline.

<button class="hj-button hjp-theme_light"><!----></button>
<button class="hj-button hjp-theme_dark hjp-size_large"><!----></button>

$foreground-color-map: (
  light: black,
  dark: white
);
$background-color-map: (
  light: white,
  dark: black
);

@include comp('button') {
  // style for .hj-button

  @each $theme in ('light', 'dark') {
    @include prop(
      (
        'theme': $theme
      )
    ) {
      color: map-get($map: $foreground-color-map, $key: $theme);
      background-color: map-get($map: $background-color-map, $key: $theme);

      @include elem('icon') {
        // style for the element icon under the different theme.
      }
    }

    @include prop(
      (
        'theme': $theme,
        'size': 'large'
      )
    ) {
      // style when the the theme is specified and the size is 'large'
    }
  }
}

The mixin prop($name-value-map-list...) will auto generate selectors:

• .hj-button.hjp-theme_light
• .hj-button.hjp-theme_dark
• .hj-button.hjp-theme_light.hjp-size_large
• .hj-button.hjp-theme_dark.hjp-size_large

Note: the prop is only for components, not for elements, usually used with @each and map.

---

status is-<status>

For components or elements, control style by boolean value.

<button class="hj-button is-raise"><!----></button>
<button class="hj-button is-raise is-active"><!----></button>

@include comp('button') {
  // style for .hj-button

  @include when('raise') {
    // ...
  }

  @include when('raise', 'active') {
    // ...
  }

  @include when-or('raise', 'active') {
    // ...
  }
}

The mixin when($status-list...) will auto generate selectors:

• .hj-button.is-raise
• .hj-button.is-raise.is-active

Them mixin when-or($status-list...) will auto generate selectors:

• .hj-button.is-raise, .hj-button.is-active

when and when-or can be used under both of components and elements.

---

rem($pixel)

The function rem($pixel) will convert a pixel number to rem number according to the global variable $root-font-size, append the unit rem to the number .

$root-font-size: 100;

:root {
  font-size: $root-font-size;
}

@include comp('foo') {
  font-size: rem(16); // will be convert to 0.16rem
}

Mobile devices

$root-font-size: 320;

:root {
  font-size: 100vw;
}

@include comp('bar') {
  // In any different size devices
  // the width of `bar` will always be 10% of the screen width
  width: rem(32);
}

Note: you need write the font-size in the :root selector yourself

---

Others

More mixins and functions, like atom, please checkout the source code.

Snippets for VSCode: scss.json

Projects using CEP

• void-ui