JSFiddle - React, Tailwind, and code Playground

HTML

<a href="javascript:;" onmousedown="startLoop();" onmouseup="stopLoop();" >
       Start loop
</a>

JavaScript

var static loop = 1;

function startLoop() {
    while(loop ==1) {
    }
    alert("stop"); //This line is not executed
}

function stopLoop() {
    loop = 2;
}