I need a code that when CheckForZero happens for the first time, after 30 seconds happens again.

var waitForZeroInterval = setInterval (CheckForZero, 0);

function CheckForZero ()
{
    if ( (unsafeWindow.seconds == 0)  &&  (unsafeWindow.milisec == 0) )
    {
        clearInterval (waitForZeroInterval);

        var targButton  = document.getElementById ('bottone1799');
        var clickEvent  = document.createEvent ('MouseEvents');

        clickEvent.initEvent ('click', true, true);
        targButton.dispatchEvent (clickEvent);
    }
};