# CustomElement

A renderless component to aid with the creation of HTML custom elements a.k.a
WebComponents.

All of the CustomElement component arguments are only used at construction
time (within the components constructor) therefore they are, by design, static.
You shouldn't be dynamically updating these values at all. They are only for
type checking and documention purposes and therefore once defined/hardcoded
they should only change if you as the author wishes to change them.

The component is built from various other components, also see their documentaton
for further details (`<ShadowHost />`, `<ShadowTemplate />`).

```hbs preview-template
<CustomElement
  @element="x-component"
  @attrs={{array
    (array 'type' '"awesome" | "sauce"' 'awesome' 'Set the type of the x-component')
    (array 'x' 'number' 0 'The x-ness of the x-component')
  }}
  @cssprops={{array
    (array '--awesome-x-sauce' 'length' '[x]' 'Makes the x-ness of the sauce available to CSS, automatically synced/tracked from the x attributes')
    (array '--awesome-color' 'color' undefined 'This CSS property can be used to set the color of the awesome')
  }}
  @cssparts={{array
    (array 'base' 'Style base from The Outside via ::part(base)')
  }}
  @slots={{array
    (array 'header' "You'll want to document the slots also")
    (array '' 'Including the default slot')
  }}
as |custom element|>
  <x-component
    {{did-insert custom.connect}}
    {{will-destroy custom.disconnect}}
    aria-hidden="true"
    ...attributes
  >
    <custom.Template
      @styles={{css-map
      }}
    >
      <div part="base"
        data-x={{element.attrs.x}}
        data-type={{element.attrs.type}}
      >
        <slot name="header"></slot>
        <slot></slot>
      </div>
    </custom.Template>
  </x-component>
</CustomElement>

```

## Arguments

All `descriptions` in attributes will be compiled out at build time as well as the `@description` attribute itself.

| Attribute     | Type           | Default | Description                                                                |
| :------------ | :------------- | :------ | :------------------------------------------------------------------------- |
| element       | string         |         | The custom tag to be used for the custom element. Must include a dash      |
| description   | string         |         | Short 1 line description for the element. Think "git commit title" style   |
| attrs         | attrInfo[]     |         | An array of attributes that can be used on the element                     |
| slots         | slotsInfo[]    |         | An array of slots that can be used for the element (100% compiled out)     |
| cssprops      | cssPropsInfo[] |         | An array of CSS properties that are relevant to the component              |
| cssparts      | cssPartsInfo[] |         | An array of CSS parts that can be used for the element (100% compiled out) |
| args          | argsInfo[]     |         | An array of Glimmer arguments used for the component (100% compiled out)   |

## Exports

### custom

| Attribute  | Type     | Description                                                                         |
| :--------- | :------- | :---------------------------------------------------------------------------------- |
| connect    | function | A did-insert-able callback for tagging an element to be used for the custom element |
| disconnect | function | A will-destroy-able callback for destroying an element used for the custom element  |

### element

| Attribute  | Type     | Description                                                                      |
| :--------- | :------- | :------------------------------------------------------------------------------- |
| attributes | object   | An object containing a reference to all the custom elements' observed properties |
| *          |          | All other properties proxy through to the CustomElements class                   |


