HTML
1
Вклад в тег
<p id="timer1">00:00:00</p>
document.getElementById("timer1").innerHTML = "00:00:01";
document.getElementById("timer1").innerHTML = hour + ":" + minute + ":" + seconds;
или это:
var dv = ":";
document.getElementById("timer1").innerHTML = hour + dv + minute + dv + seconds;