Java-Scripts.net

Online Timer

Set it and forget it. This script calculates the target end time based on user input and updates the display every second until the deadline is reached.

00:00:00
Set time and click Start

Copy the Script

<script>
var timerInterval;

function startCountdown() {
    // Get inputs (simplified)
    var m = parseInt(document.getElementById("min").value) || 0;
    var s = parseInt(document.getElementById("sec").value) || 0;
    
    // Calculate total seconds
    var totalTime = (m * 60) + s;
    var display = document.getElementById("display");

    clearInterval(timerInterval); // Clear existing

    timerInterval = setInterval(function() {
        if (totalTime <= 0) {
            clearInterval(timerInterval);
            display.innerHTML = "Time's Up!";
            alert("Timer Finished!");
        } else {
            totalTime--;
            var mins = Math.floor(totalTime / 60);
            var secs = totalTime % 60;
            // Pad with leading zero
            display.innerHTML = (mins < 10 ? "0" : "") + mins + ":" + (secs < 10 ? "0" : "") + secs;
        }
    }, 1000);
}
</script>

<input id="min" placeholder="Min"> <input id="sec" placeholder="Sec">
<button onclick="startCountdown()">Start</button>
<div id="display">00:00</div>

Frequently Asked Questions

Yes, `setInterval` continues running even if you switch tabs, though modern browsers may reduce the update frequency (throttling) to save battery. The end time will still be accurate.

Yes. You can add `new Audio('beep.mp3').play()` inside the `if (distance < 0)` block to trigger an audio alarm.

Simply use `clearInterval(timerId)` to stop the loop and reset the display text back to '00:00:00'.