Generator for a sitemap.xml in Node.js

sitemap-generator.js

"use strict";

const DOMAIN = "example.com";
const URLS_PER_FILE = 40000;
const fs = require("fs");
const readline = require("readline");

const rd = readline.createInterface({
    input: fs.createReadStream(`${__dirname}/input/ids-and-dates.txt`)
});

function writeSitemap(sitemapNumber, urls) {
    const writeStream = fs.createWriteStream(`${__dirname}/output/sitemap-${sitemapNumber}.xml`);
    writeStream.on("finish", () => {
        console.log(`Wrote sitemap-${sitemapNumber}.xml`);
    });

    writeStream.write(`<?xml version="1.0" encoding="UTF-8"?>\n`);
    writeStream.write(`<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:xhtml="http://www.w3.org/1999/xhtml">\n`);
    for (const url of urls) {
        writeStream.write(url + "\n");
    }
    writeStream.write(`</urlset> `);
    writeStream.end();
}

let counter = 1;
let urlBuffer = [];
rd.on("line", function (line) {
    const [storyId, date] = line.split(",");
    urlBuffer.push(`
        <url>
            <loc>https://${DOMAIN}/stories/${storyId}/</loc>
            <lastmod>${date}</lastmod>
            <xhtml:link rel="alternate" media="only screen and (max-width: 640px)" href="https://${DOMAIN}/m/stories/${storyId}/" />
        </url>
    `);

    if (counter % URLS_PER_FILE === 0) {
        writeSitemap((counter / URLS_PER_FILE), urlBuffer);
        urlBuffer = [];
    }

    counter ++;
});

rd.on("close", () => {
    if (urlBuffer.length > 0) {
        writeSitemap(Math.ceil(counter / URLS_PER_FILE), urlBuffer);
    }
});