JSFiddle - React, Tailwind, and code Playground

HTML

Campo Uno: <input type = "text" id="AutoUser" onKeyUp="Tiempo();" />
<br>Otro Campo que no me interesa: <input type = "text" />

CSS

input{
    width: 15em;
}

JavaScript

//function Tiempo(){    
    var input = document.getElementById("AutoUser"),
        intervalo,
        disabled = function(){
            return setTimeout(function(){
               Desactivar();
            }, 1500);
        };
        
    input.addEventListener("keyup", function(){
        clearTimeout(intervalo);
        intervalo = disabled();
    }, false);    
//}
    
function Desactivar(){
    document.getElementById("AutoUser").disabled = true;    
    // MAS FUNCIONES AQUÍ
}