let hour = 0;
let minute = 0;
let second = 0;
let millisecond = 0;

let cron;

function iniciarCronometro() {
    pausarCronometro();
    cron = setInterval(() => {
        timer();
    }, 10);
}

function pausarCronometro() {
    clearInterval(cron);
}

function resetarCronometro() {
    hour = 0;
    minute = 0;
    second = 0;
    millisecond = 0;
    document.getElementById("hour").innerText = "00";
    document.getElementById("minute").innerText = "00";
    document.getElementById("second").innerText = "00";
    }

function timer() {
    if ((millisecond += 10) == 1000) {
        millisecond = 0;
        second++;
    }
    if (second == 60) {
        second = 0;
        minute++;
    }
    if (minute == 60) {
        minute = 0;
        hour++;
    }
    document.getElementById("hour").innerText = returnData(hour);
    document.getElementById("minute").innerText = returnData(minute);
    document.getElementById("second").innerText = returnData(second);
}

function returnData(input) {
    return input > 10 ? input : `0${input}`;
}