Add lastmod to sitemap.xml

[iliamrv]

Hi, I'd like to change sitemap generation script to add some valuable details for Google information there.

[lastmod]

It is important for my project as I have hundreds of pages with different priority for indexation.

Could you help me please?

[enpitsuLin]

I may have misunderstood, You need to provide lastmod for each page instead of using a uniform build time, right?

We could probably simply use the file last modified date as lastmod or have you improved on frontmatter?

you can try this

scripts/generate-sitemap.js

const fs = require('fs')
const globby = require('globby')
const matter = require('gray-matter')
const prettier = require('prettier')
const siteMetadata = require('../data/siteMetadata')

;(async () => {
  const prettierConfig = await prettier.resolveConfig('./.prettierrc.js')
  const pages = await globby([
    'pages/*.js',
    'pages/*.tsx',
    'data/blog/**/*.mdx',
    'data/blog/**/*.md',
    'public/tags/**/*.xml',
    '!pages/_*.js',
    '!pages/_*.tsx',
    '!pages/api'
  ])

  const sitemap = `
        <?xml version="1.0" encoding="UTF-8"?>
        <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
            ${pages
              .map((page) => {
                let lastmod = new Date().toJSON()
                // Exclude drafts from the sitemap
                if (page.search('.md') >= 1 && fs.existsSync(page)) {
                  const source = fs.readFileSync(page, 'utf8')
                  const fm = matter(source)
                  // Use the frontmatter that page has lastmod in frontmatter instead of mtime in file system
                  if (fm.data.lastmod) {
                    lastmod = fm.data.lastmod
                  } else {
                    lastmod = fs.statSync(page).mtime.toJSON()
                  }
                  if (fm.data.draft) {
                    return
                  }
                  if (fm.data.canonicalUrl) {
                    return
                  }
                }
                const path = page
                  .replace('pages/', '/')
                  .replace('data/blog', '/blog')
                  .replace('public/', '/')
                  .replace('.js', '')
                  .replace('.tsx', '')
                  .replace('.mdx', '')
                  .replace('.md', '')
                  .replace('/feed.xml', '')
                const route = path === '/index' ? '' : path

                if (page.search('pages/404.') > -1 || page.search(`pages/blog/[...slug].`) > -1) {
                  return
                }
                return `
                        <url>
                            <loc>${siteMetadata.siteUrl}${route}</loc>
                            <lastmod>${lastmod}</lastmod>
                        </url>
                    `
              })
              .join('')}
        </urlset>
    `

  const formatted = prettier.format(sitemap, {
    ...prettierConfig,
    parser: 'html'
  })

  // eslint-disable-next-line no-sync
  fs.writeFileSync('public/sitemap.xml', formatted)
})()

---

Here's an easy way to do it

you can simply replace scripts/generate-sitemap.js to add lastmod to the sitemap

here is code

scripts/generate-sitemap.js

const fs = require('fs')
const globby = require('globby')
const matter = require('gray-matter')
const prettier = require('prettier')
const siteMetadata = require('../data/siteMetadata')

;(async () => {
  const prettierConfig = await prettier.resolveConfig('./.prettierrc.js')
  const pages = await globby([
    'pages/*.js',
    'pages/*.tsx',
    'data/blog/**/*.mdx',
    'data/blog/**/*.md',
    'public/tags/**/*.xml',
    '!pages/_*.js',
    '!pages/_*.tsx',
    '!pages/api'
  ])
  const lastmod = new Date().toJSON()

  const sitemap = `
        <?xml version="1.0" encoding="UTF-8"?>
        <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
            ${pages
              .map((page) => {
                // Exclude drafts from the sitemap
                if (page.search('.md') >= 1 && fs.existsSync(page)) {
                  const source = fs.readFileSync(page, 'utf8')
                  const fm = matter(source)
                  if (fm.data.draft) {
                    return
                  }
                  if (fm.data.canonicalUrl) {
                    return
                  }
                }
                const path = page
                  .replace('pages/', '/')
                  .replace('data/blog', '/blog')
                  .replace('public/', '/')
                  .replace('.js', '')
                  .replace('.tsx', '')
                  .replace('.mdx', '')
                  .replace('.md', '')
                  .replace('/feed.xml', '')
                const route = path === '/index' ? '' : path

                if (page.search('pages/404.') > -1 || page.search(`pages/blog/[...slug].`) > -1) {
                  return
                }
                return `
                        <url>
                            <loc>${siteMetadata.siteUrl}${route}</loc>
                            <lastmod>${lastmod}</lastmod>
                        </url>
                    `
              })
              .join('')}
        </urlset>
    `

  const formatted = prettier.format(sitemap, {
    ...prettierConfig,
    parser: 'html'
  })

  // eslint-disable-next-line no-sync
  fs.writeFileSync('public/sitemap.xml', formatted)
})()

and also a more next.js style implementation in my blog - source

[iliamrv]

thanks so much!