Q:

Reload page every hour on the :00 minute and the :30 minute

I need to reload a page's content every 30 minutes (on the hour and 30 minutes past the hour). I'm thinking JavaScript for this, and I've tried the code below, but it goes into an endless loop. I'm not sure how to change it to avoid the loop. 
meta tags won't help since they can't execute on a certain minute. 
function refreshContent() {
    var tDate = new Date();
    thisHour = tDate.getHours();
    thisMinute = tDate.getMinutes();
    thisSecond = tDate.getSeconds();
    setTimeout("refreshContent()",60000); // in milliseconds = 1 minute

    if ( thisMinute == 0 || thisMinute == 30 ) {
        location.reload();
    }

}
refreshContent();

A:

You'll need to set only one timer and calculate when is the next time to refresh. That way you can prevent the page from repeatedly reloading itself when the page is loaded exactly at :00 or :30.
var minute = new Date().getMinutes(),
    nextRefresh = (30 - (minute % 30)) * 60 * 1000;

setTimeout( function() { location.reload(); }, nextRefresh );

30 - (minute % 30) calculates how many minutes until the next half hour and * 60 * 1000 converts that into milliseconds. After reload is triggered the timer is set to 30 minutes.

