NextJS Sitemap Handler

sitemap.js

export default function handler(req, res) {
    // getPosts is a fn that returns all the posts, you should already have this for a markdown/mdx site
    const posts = getPosts();

    res.statusCode = 200
    res.setHeader('Content-Type', 'text/xml')
    // Instructing the Vercel edge to cache the file
    res.setHeader('Cache-control', 'stale-while-revalidate, s-maxage=3600')

    // generate sitemap here
    const xml = `<?xml version="1.0" encoding="UTF-8"?>
        <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
        ${posts.map(({ slug, data }) => `
            <url>
                <loc>${`https://yoursitename.com/${slug}`}</loc>
                <lastmod>${new Date(data.date).toISOString()}</lastmod>
            </url>` ).join('')}
        </urlset>`
    res.end(xml)
}