shadowfacts.net/lib/generate/categories.ts

import { Page, PostMetadata } from "../metadata";
import generatePaginated from "./paginated";

export default async function(posts: Page[]): Promise<Map<string, Page[]>> {
	const categories = new Map<string, Page[]>();

	for (const post of posts) {
		const category = (<PostMetadata>post.metadata).category;
		if (!categories.has(category)) {
			categories.set(category, []);
		}
		categories.get(category)!.push(post);
	}

	categories.forEach((categoryPosts, category) => {
		generatePaginated(categoryPosts, `/${category}/`, "site/category.html.ejs", {
			category
		}, {
			title: `${category} posts`
		});
	});

	return categories;
}