JSFiddle - React, Tailwind, and code Playground

HTML

<p>test1</p>
<input type="text" id="Submit">
<input type="text" id="Time">
<hr>
<p>test2</p>
<input type="text" id="Submit2">
<input type="text" id="Time2">

JavaScript

ms = 30; // 1000 ?
num = 1;
start = new Date();

function test()
{
    num+=ms;
    document.getElementById('Submit').value = num;
    if (num < 4000)
        window.setTimeout(test, ms);
    else 
        document.getElementById('Time').value = new Date() - start;
}

test()



ms2 = 30; // 1000 ?
num2 = 1;
start2 = new Date();
dueTo = new Date(+new Date()+4000);

function test2()
{
    num2+=ms2;
    document.getElementById('Submit2').value = num2;
    if (new Date() < dueTo)
        window.setTimeout(test2, ms2);
    else 
        document.getElementById('Time2').value = new Date() - start2;
}
test2()