Show HN: Bookmarklet to highlight recent comments in a Hacker News thread

I find myself often checking into a thread to see the latest replies, which usually means visually scanning for comments that have "minutes" in the timestamp.

I decided to automate this (and a bit extra) with a bookmarklet. Create a new bookmark in your web browser and paste the following into the URL field:

  javascript:(function() {
    const cutoffStr = prompt("Highlight posts in the last:", "1 hour");
    
    function millisForStr(s) {
      const [num, unit] = s.split(' ');
      const parsedNum = Number(num);
    
      return unit.includes('minute') ? parsedNum * 60 * 1000 
        : unit.includes('hour') ? parsedNum * 60 * 60 * 1000 
        : unit.includes('day') ? parsedNum * 24 * 60 * 60 * 1000 
        : NaN;
    }
    
    Array.from(document.querySelectorAll('.age'))
      .map(el => {
        const interval = millisForStr(el.innerText);
    
        return [el, new Date(Date.now() - interval)];
      })
      .forEach(([el, date]) => {
        const cutoff = new Date(Date.now() - millisForStr(cutoffStr));
        if (date >= cutoff) {
          el.parentElement.parentElement.parentElement.style.background = "rgba(255, 215, 0, 0.5)";
        } else {
          el.parentElement.parentElement.parentElement.style.background = null;
        }
      })
  })();

When clicked, you'll be prompted for a string of the form "1 hour" or "23 minutes" or "2 days", and after submitting you'll see all comments on the current page that fall within that interval highlighted with a gold-colored background. Let me know what you think or if you'd like any other small features!