JSFiddle - React, Tailwind, and code Playground

HTML

<p id=log>Неизвестно</p>
 <input type="number" value="123">

JavaScript

(function testit_phase1()
   {
     // Force paint of visible widget
     var num = document.getElementsByTagName("input")[0];
     num.offsetTop;
     // Force it to be hidden
     num.style.display = "none";
     num.offsetTop;
     // Set it empty and request it to be visible again.
     num.value="";
     num.style.display = "inline";
     num.offsetTop;
     // Check that it's still empty.
     var msg = "УСПЕХ";
     if (num.value != "")
       msg = "ПРОВАЛ — num.value не очищено";

     passed = (msg == "УСПЕХ");
     document.getElementById("log").innerHTML = msg;
   })();