This is sitemap.xml generator for nextjs. forked from https://gist.github.com/evantahler/ba75e277c756fce337b7370035b298e7 .

SitemapGenerator.js

#! /usr/bin/env node
// I am ./bin/buildSitemap.js

const path = require('path')
const glob = require('glob')
const fs = require('fs')

const SITE_ROOT = process.env.SITE_ROOT || 'https://nshun.net'
const SOURCE = process.env.SOURCE || path.join(__dirname, '../..', 'docs', '/**/*.html')
const DESTINATION = process.env.DESTINATION || path.join(__dirname, '../..', 'docs/static', 'sitemap.xml')

let diskPages = glob.sync(SOURCE)

let xml = ''
xml += '<?xml version="1.0" encoding="UTF-8"?>'
xml += '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">'

diskPages.forEach((page) => {
  page = path.normalize(page)

  let stats = fs.statSync(page)
  let modDate = new Date(stats.mtime)
  let lastMod = `${modDate.getFullYear()}-${('0' + (modDate.getMonth() + 1)).slice(-2)}-${('0' + modDate.getDate()).slice(-2)}`

  console.log(path.join(__dirname, '../..', 'docs')+' in '+page)
  page = page.replace(path.join(__dirname, '../..', 'docs'), '')
  console.log(page)
  page = page.replace(/.html$/, '')
  page = `${SITE_ROOT}${page}`

  if (/.*[\/\\]index$/.test(page)) {
    page = page.replace(/(.*)index$/, '$1')
  }

  page = page.split(path.sep).join('/')

  xml += '<url>'
  xml += `<loc>${page}</loc>`
  xml += `<lastmod>${lastMod}</lastmod>`
  xml += `<changefreq>always</changefreq>`
  xml += `<priority>0.5</priority>`
  xml += '</url>'
})

xml += '</urlset>'

fs.writeFileSync(DESTINATION, xml)

console.log(`Wrote sitemap for ${diskPages.length} pages to ${DESTINATION}`)