metatag-diff: Compare (diff) metatags of prod and stage host version given an article slug.

index.js

const fetch = require("node-fetch");
const cheerio = require("cheerio");
const diff = require("diff");
const colors = require("colors");

const inputSlug = process.argv[2];

const notImplemented = [
  "[rel=amphtml]",
  "[property='og:image']",
  "[property='og:description']"
];
const PROD_HOST = "https://some-prod-host.example/";
const DEV_HOST = "https://basic:auth@some-stage-host.example/";

function fetchHtml(slug) {
  async function getHtml(url) {
    const response = await fetch(url);
    return await response.text();
  }

  return Promise.all([
    getHtml(`${PROD_HOST}${slug}`),
    getHtml(`${DEV_HOST}${slug}`)
  ]);
}

function extractMetatags(html) {
  const $ = cheerio.load(html);
  return $("meta, link, title")
    .not(notImplemented.join(", "))
    .map((i, tag) => $.html(tag).trim())
    .get();
}

function compare([prodTags, stageTags]) {
  prodTags.forEach((check, index) => {
    const parts = diff.diffChars(check, stageTags[index] || "");
    parts.forEach(part => {
      const color = part.added ? "green" : part.removed ? "red" : "grey";
      // This uses the extended String prototype (see `colors` package)
      process.stderr.write(part.value[color]);
    });
    console.log();
  });
}

function main(slug) {
  fetchHtml(slug)
    .then(responses => responses.map(extractMetatags))
    .then(metatags => metatags.map(metatag => metatag.sort()))
    .then(compare)
    .catch(err => console.log(err));
}

main(inputSlug);

package.json

{
  "name": "metatag-diff",
  "version": "1.0.0",
  "description": "Compare (diff) metatags of prod and stage host version given an article slug.",
  "main": "index.js",
  "scripts": {
    "start": "node index.js"
  },
  "author": "leomelzer",
  "license": "UNLICENSED",
  "dependencies": {
    "cheerio": "^1.0.0-rc.2",
    "colors": "^1.3.0",
    "diff": "^3.5.0",
    "node-fetch": "^2.1.2"
  },
  "devDependencies": {
    "eslint": "^4.19.1",
    "prettier": "^1.13.5"
  }
}