Question

I created a small script to display the time(UTC-+3.5). The problem is there that changes GMT(+4.5, +3.5) in Iran every six months in year, and changes Time is pulled back and forth (Daylight Saving)
How i set yourself clock with change GMT in iran? what do i do? (now GMT in iran is +4.5)

EXAMPLE: my code-jsfiddle

var int = self.setInterval("clock()", 1000);

function clock() {
    var d = calcTime('+4.5')
    var t = d.toLocaleTimeString();
    document.getElementById("clock").innerHTML = t;
}

function calcTime(offset) {
    d = new Date();
    utc = d.getTime() + (d.getTimezoneOffset() * 60000);
    nd = new Date(utc + (3600000 * offset));

    return nd;
}

With respect

Answer 1

Fiddle Example

<script type="text/javascript">
var int = self.setInterval("clock()", 1000);

function clock() {
    var d = calcTime('+4.5')
    var t = d.toLocaleTimeString();
    document.getElementById("clock").innerHTML = t;
}

function calcTime(offset) {
    d = new Date();
    ds = new Date(); // new Daylight Savings Time object
    ds.setMonth(9); // Set month to september
    ds.setDate(21); // set day to 21st
    if(d > ds){ // if current date is past the daylight savings date minus one from the offset
        offset = eval(offset - 1);
    }
    utc = d.getTime() + (d.getTimezoneOffset() * 60000);
    nd = new Date(utc + (3600000 * offset));

    return nd;
}
</script>

<b id="clock"></b>

This works. It will check if the date is currently past September 21st and if it is it will -4.5 from GMT otherwise 3.5

it is not the cleanest code i’ve ever written, I just modified yours. however you can see how it is done now.