var myTimeout;
myTimeout = window.setTimeout("showTime();", 1000);

function showTime() {
    myTimeout = window.setTimeout("showTime();", 5000);

    myTime = new Date();
    var myGMTHours = myTime.getHours() + myTime.getTimezoneOffset()/60;
    var myMinutes;
    if (myTime.getMinutes() < 10) {
        myMinutes = '0' + myTime.getMinutes();
    } else {
        myMinutes = myTime.getMinutes();
    }

    window.document.getElementById("timeParis").innerHTML = (myGMTHours + 1) + ":" + myMinutes;
    window.document.getElementById("timeLondon").innerHTML = (myGMTHours + 0) + ":" + myMinutes;
    window.document.getElementById("timeNewYork").innerHTML = (myGMTHours - 4) + ":" + myMinutes;

}