Another simple chrome extension to track your YouTube watch time

manifest.json

{
  "manifest_version": 3,
  "name": "count daily youtube watch time",
  "description": "made by sam",
  "version": "0.0.1",
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*"
      ],
      "js": ["timer.js"]
    }
  ]
}

timer.js

// Displays a watch time in the corner of your screen.
const timeName = 'sam_watchTime_' + (new Date().setHours(0, 0, 0, 0));
setInterval(() => {
  localStorage.setItem(timeName, parseInt(localStorage.getItem(timeName) || 0) + 500);
}, 500);

window.addEventListener('load', () => {
  setTimeout(() => {
    const timerElem = document.createElement('div');
    timerElem.setAttribute('style', 'position:fixed;right:0;bottom:0;color:white;background:black;font-size:20px;');
    document.body.append(timerElem);
    setInterval(() => {
      const total = Math.floor((parseInt(localStorage.getItem(timeName) || 0) / 1000) / 60);
      timerElem.innerText = `Watched for: ${total} minutes today`;
    }, 1000);
  }, 2000)  
});

How to count the total time (and maybe even the number of videos watched) in a month, to make sure the premium subscription was worth it? :)