startday = new Date();
clockStart = startday.getTime();

function Timer() { 
var myTime = new Date();         
var timeNow = myTime.getTime();          
var timeDiff = timeNow - clockStart;         
this.diffSecs  =timeDiff/1000;
return(this.diffSecs);
}

function ShowLoadTime() {
load_time ="" + Timer();
load_time =", открыта за: " + load_time.substring(0,4);
indicator_time.innerText = indicator_time.innerText + load_time + " секунды";
}

window.onload =ShowLoadTime;