Area.svelte component

<!--
  @component
  Generates an SVG area shape.
 -->
<script>
  import { getContext } from 'svelte';

  const { data, xGet, yGet, xScale, yScale, extents } = getContext('LayerCake');

  /** @type {String} [fill='#ab00d610'] - The shape's fill color. This is technically optional because it comes with a default value but you'll likely want to replace it with your own color. */
  export let fill = '#ab00d610';

  $: path =
    'M' +
    $data
      .map(d => {
        return $xGet(d) + ',' + $yGet(d);
      })
      .join('L');

  /**  @type {String} **/
  let area;

  $: {
    const yRange = $yScale.range();
    area =
      path +
      ('L' +
        $xScale($extents.x ? $extents.x[1] : 0) +
        ',' +
        yRange[0] +
        'L' +
        $xScale($extents.x ? $extents.x[0] : 0) +
        ',' +
        yRange[0] +
        'Z');
  }
</script>

<path class="path-area" d={area} {fill}></path>