34 lines
1.1 KiB
TypeScript
34 lines
1.1 KiB
TypeScript
import type { Root, Paragraph, PhrasingContent } from 'mdast';
|
|
import type { VFile } from 'vfile';
|
|
import { visit } from 'unist-util-visit';
|
|
import { toString } from 'mdast-util-to-string';
|
|
|
|
|
|
export function remarkDescription() {
|
|
return (tree: Root, vfile: VFile) => {
|
|
let description: string | null = null;
|
|
|
|
visit(tree, 'paragraph', (node: Paragraph) => {
|
|
if (description !== null) return;
|
|
description = summarize(node);
|
|
});
|
|
|
|
// Astro exposes this as `remarkPluginFrontmatter` from render()
|
|
const astro = (vfile.data.astro ??= { frontmatter: {} }) as { frontmatter: Record<string, unknown> };
|
|
astro.frontmatter.description = description;
|
|
};
|
|
}
|
|
|
|
|
|
/**
|
|
* Convert a paragraph node to a plain-text string, stripping any
|
|
* MDX JSX elements (e.g. <Sidenote>) so their content doesn't
|
|
* leak into the summary.
|
|
*/
|
|
function summarize(par: Paragraph): string {
|
|
const filtered = par.children.filter(
|
|
(child: PhrasingContent) => !(child.type as string).startsWith('mdxJsx')
|
|
);
|
|
return toString({ type: 'paragraph', children: filtered });
|
|
}
|