Next.js sitemap

sitemap.ts

const { promises: fs } = require("fs");
const path = require("path");

interface FileInfo {
  page: string;
  lastModified: Date;
}

const pagesDir = `${process.cwd()}/src/pages/`;

async function getAllFiles(): Promise<FileInfo[]> {
  const files: FileInfo[] = [];
  for await (const file of getFiles(pagesDir)) files.push(file);
  return files;
}

async function* getFiles(dir: string): AsyncGenerator<FileInfo> {
  // Get all files of the current directory & iterate over them
  const files = await fs.readdir(dir);
  for (const file of files) {
    // Construct whole file-path & retrieve file's stats
    const filePath = `${dir}${file}`;
    const fileStat = await fs.stat(filePath);

    if (!isValid(file, dir, fileStat)) continue;

    if (fileStat.isDirectory()) {
      // Recurse one folder deeper
      for await (const innerFile of getFiles(`${filePath}/`)) yield innerFile;
    } else {
      // Check if page is dynamic route
      if (/\[.*\]\.(jsx?|tsx)/.test(file)) {
        const page = require(filePath);
        // Dynamic paths are generated at build time
        if (page.getStaticPaths) {
          const {
            paths,
          }: {
            paths: { params: { [key: string]: string } }[];
          } = page.getStaticPaths();
          for (const { params } of paths) {
            let dynamicPath = file;
            for (const [param, value] of Object.entries(params))
              dynamicPath = dynamicPath.replace(`[${param}]`, value);
            yield {
              page: `${cleanFileName(`${dir}${dynamicPath}`)}`,
              lastModified: fileStat.mtime,
            };
          }
        } else {
          const page = `/${cleanFileName(filePath)}`;
          console.info(
            `\`/${page}\` is dynamic page and must be obtained at runtime`
          );
        }
      }
      // Page is normal route
      else {
        yield {
          page: `/${cleanFileName(filePath)}`,
          lastModified: fileStat.mtime,
        };
      }
    }
  }
}

const isValid = (file: string, parentDir: string, fileStat): boolean => {
  const isRoot = parentDir === pagesDir;
  const isDir = fileStat.isDirectory();

  if (isRoot && isDir && file === "api") return false;

  if (isRoot && !isDir && /^404\.(jsx?|tsx)$/.test(file)) return false;

  if (file.startsWith("_")) return false;

  if (file)
    if (
      !file.endsWith(".js") &&
      !file.endsWith(".jsx") &&
      !file.endsWith(".tsx") &&
      !file.endsWith(".md") &&
      !file.endsWith(".mdx")
    )
      return false;

  return true;
};

const cleanFileName = (fileName: string): string => {
  const fixed = fileName
    .substr(0, fileName.lastIndexOf("."))
    .replace(pagesDir, "");
  return fixed.endsWith("/index") || fixed === "index"
    ? fixed.substr(0, fixed.lastIndexOf("/") + 1)
    : fixed;
};

const formatDate = (date: Date): string => {
  let month = String(date.getMonth() + 1),
    day = String(date.getDate()),
    year = date.getFullYear();

  if (month.length < 2) month = `0${month}`;
  if (day.length < 2) day = `0${day}`;

  return [year, month, day].join("-");
};

export function createSiteMap(items: FileInfo[]): string {
  const lines = [
    '<?xml version="1.0" encoding="UTF-8"?>',
    '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"> ',
  ];
  for (const { page, lastModified } of items) {
    lines.push("<url>");
    lines.push(`<loc>${page}</loc>`);
    lines.push(`<lastmod>${formatDate(lastModified)}</lastmod>`);
    lines.push("</url>");
  }
  lines.push("</urlset>");
  return lines.join("");
}

export const writeSiteMap = (sitemap: string) => {
  const parentDir = path.basename(path.dirname(pagesDir));
  const publicDir = `${parentDir}public/`;
  if (!fs.existsSync(publicDir)) fs.mkdirSync(publicDir);
  fs.writeFileSync(`${publicDir}sitemap.xml`, sitemap);
};

export default getAllFiles;