README.md

Host CSS Variable

This package enable to host-scoped css variable(custom property) by using hvar(--name).

Installation

• Webpack
• Angular

Webpack

Install host-css-variable to dev dependencies

$ npm i -D host-css-variable

and add host-css-variable/loader to your webpack.config.js

module.exports = {
	//...... 
  module: {
    rules: [
      {
        test: /\.scss$/,
        use: [
          // Add 'host-css-variable' after the SCSS Loaders.
          { loader: 'host-css-variable' }
        ],
      }
    ],
  },
}

Angular

If you use Angular, you can setup by ng add command.

$ ng add angular-host-css-variable

Please read angular-host-css-variable.

Usage Example

child.component.scss

@import '~host-css-variable/host-variable';
$host: host('child');

:host {
  // Define host css variable and default value. It can be accessed in host scope.
  @include hvar(--width, 200px);
  @include hvar(--height, 100vh);
}

:host {
  display: block;
  // Using defined host css variable.
  width: hvar(--width);
  height: hvar(--height);
}

parent.component.scss

@import '~host-css-variable/host-variable';
$host: host('parent');

:host {
  @include hvar(--width, 1200px);
  @include hvar(--height, 100vh);
}

:host {
  display: block
  width: hvar(--width);
  height: hvar(--height);

  child {
    --width: calc(hvar(--width) / 2);
    --height: hvar(--height);
  }
}

grandparent.component.scss

@import '~host-css-variable/host-variable';
$host: host('grandparent');

:host {
  @include hvar(--width, 1920px);
  @include hvar(--height, 100vh);
}

:host {
  display: block
  width: hvar(--width);
  height: hvar(--height);

  parent {
    --width: 1600px;
    --height: hvar(--height);
  }
}

In this case, the width of components is following.

components	width	height
grandparent	1920px	100vh
parent	1600px	100vh
child	800px	100vh