time validation inp

<!DOCTYPE html>
<html>
<body>

<p>This demo used to validate time with 12 hours format</p>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

<script>
function myFunction() {
    var regexp = /^(0?[1-9]|1[012])(:[0-5]\d) [APap][mM]$/;
    var res = regexp.test('12:00 AM'); //try with alphabets or wrong format
    document.getElementById("demo").innerHTML = res;
}
</script>

</body>
</html>


$time_in_12_hour_format  = date("g:i a", strtotime("13:30"));

// 12-hour time to 24-hour time
$time_in_24_hour_format  = date("H:i", strtotime("1:30 PM"));