Bookmarklet to display estimated YouTube Dislikes based on returnyoutubedislikeapi.com. Paste as the URL inside a bookmark.

👎🏻 YT Dislikes.js

javascript:void function(){
  let a=new URL(location).searchParams.get("v"),
      b=new Intl.NumberFormat("en-US"),
      c=trustedTypes.createPolicy("forceInner", { createHTML: a => a });
  fetch(`https://returnyoutubedislikeapi.com/Votes?videoId=${a}`).then(a=>a?.text?.())
    .then(a => "{" === a[0] && JSON.parse(a) || a)
    .then(a => {
      console.log("dislikes",a); 
      a?.dislikes && document.body.insertAdjacentHTML(
        "beforeend",
        c.createHTML(`<div style="font-size:2rem;color:#ff0;position:absolute;right:2rem;top:8rem;z-index:10000;">
          ${b.format(a.dislikes)} dislikes
        </div>`)
      )
    })
}();

👎🏻 YT Dislikes.min.js

javascript:void function(){let a=new URL(location).searchParams.get("v"),b=new Intl.NumberFormat("en-US"),c=trustedTypes.createPolicy("forceInner",{createHTML:a=>a});fetch(`https://returnyoutubedislikeapi.com/Votes%3FvideoId=${a}`).then(a=>a%3F.text%3F.()).then(a=>"{"===a[0]%26%26JSON.parse(a)||a).then(a=>{console.log("dislikes",a),a%3F.dislikes%26%26document.body.insertAdjacentHTML("beforeend",c.createHTML(`<div style="font-size:2rem;color:%23ff0;position:absolute;right:2rem;top:8rem;z-index:10000;">${b.format(a.dislikes)} dislikes</div>`))})}();