measure the time for opening a perticular web page on the cl

[wxdqz]

I wanna measure the time taken by browser to connect a web url and then load it fully. Presently I'm using this code snippet which I think is not giving exact time.
currentDate1 = new Date();
var startTime = currentDate1.getTime();
var win = open(document.Timingform.URL.value);
currentDate2 = new Date();
document.Timingform.hiddenTiming.value = (currentDate2.getTime()-startTime);
win.close();

can u suggest some way to do it?