Multilingual Sapper sitemap.xml with day.js

sitemap.xml.js

import dayjs from "dayjs"
import { supportedLanguages } from "../config"

const fs = require("fs")
const path = require("path")
const cwd = process.cwd()
const matter = require("gray-matter")
const util = require("util")
const glob = require("glob")

const stat = util.promisify(fs.stat)

const BASE_URL = "https://rememo.io" // Change this with ur domain
const pages = [""]
const POSTS_DIR = path.join(cwd, "src/")
let svelteRoutes = []

const i18nFolder = "[lang]"
const notPages = [`/${i18nFolder}`, "/p"] // Urls to exclude from sitemap
const extraFilter = (file) => !notPages.includes(file)
const directory = path.join(cwd, "src/routes")
const unixStyleDirectory = directory.replace(/\\/gi, "/")

const getRoutes = async (files) => {
  // get all the routes in the directory and index files stats (last modified)
  const mapped = await Promise.all(
    files.map(async (file) => ({
      last_modified: dayjs(await stat(file).mtime).format("YYYY-MM-DD"),
      filepath: file.replace(unixStyleDirectory, "").replace(/\/index.svelte/gi, ""),
    }))
  )

  // remove every route that has ID in it - those will be rendered after API call
  const filtered = await Promise.all(
    mapped.filter(
      ({ filepath }) => filepath.length && !filepath?.includes("id") && extraFilter(filepath)
    )
  )

  // replace [lang] with available languages
  const reduced = await Promise.all(
    filtered.reduce((acc = [], current) => {
      if (current.filepath.includes(i18nFolder)) {
        const i18nRoutes = supportedLanguages.map((lang) =>
          current.filepath.replace("[lang]", lang)
        )
        acc.push(
          i18nRoutes.map((route) => ({ filepath: route, last_modified: current.last_modified }))
        )
      } else {
        acc.push(current)
      }
      return acc
    }, [])
  )
  /* 
    Output will look something like this:
    [ 
      [
        { filepath: '/ru/shortcuts', last_modified: '2021-11-20' },
        { filepath: '/en/shortcuts', last_modified: '2021-11-20' },
        { filepath: '/th/shortcuts', last_modified: '2021-11-20' }
      ],
      { last_modified: '2021-11-20', filepath: '/changelog' },
      { last_modified: '2021-11-20', filepath: '/privacy' },
    ]
  */
  return reduced
}

glob(directory + "/**/!(_)*.svelte", {}, async (err, files) => {
  svelteRoutes = await getRoutes(files)
})

const render = (pages, posts) => `<?xml version="1.0" encoding="UTF-8" ?>
<urlset 
  xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
  xmlns:xhtml="http://www.w3.org/1999/xhtml"
>
  ${svelteRoutes
    .map((route) => {
      if (Array.isArray(route)) {
        return `<url>
            ${route
              .map((r, i) => {
                if (i === 0) {
                  return `<loc>${BASE_URL}${r.filepath}</loc>`
                } else {
                  return `<xhtml:link rel="alternate" hreflang="${
                    r.filepath.split("/")[1]
                  }" href="${BASE_URL}${r.filepath}"/>`
                }
              })
              .join("\n")}
            <lastmod>${route[0].last_modified}</lastmod>
          </url>`
      } else {
        return `<url>
            <loc>
              ${BASE_URL}${route.filepath}
            </loc>
            <lastmod>${route.last_modified}</lastmod>
          </url>`
      }
    })
    .join("\n")}
</urlset>
`

export function get(req, res, next) {
  res.setHeader("Cache-Control", `max-age=0, s-max-age=${600}`) // 10 minutes
  res.setHeader("Content-Type", "application/xml")

  const sitemap = render(pages, posts)
  res.end(sitemap)
}