[Javascript] Survey and elapsed time behind the scenes

[Paul Novitski]

At 07:12 PM 6/3/2004, dev at qroute.net wrote:
>When the page that has the survey form loads, I plan to start a javascript
>timer behind the scenes and to measure time it takes for the user to respond
>all the questions. Of course, no one is going to know about it. ;-)
>
>At the end, right at onSubmit, a hidden field will be populated with the
>elapaed time info at that time so the elapsed time as well can be shipped
>from the client to the server.


My personal approach would be simply to time-stamp the start & finish and 
pass those values to my server-side script.  You could define the start as 
either the body.onload() event or the first input field the user interacts 
with, and the final event is the form.submit() event.

(If you're generating your page from a server-side script, you might 
consider doing the elapsed time calculation entirely from there:  download 
the page with the BeginTime field pre-set and subtract that time from Now() 
when the page is submitted.  That would have the advantage of allowing 
people to subimt surveys even if their browsers don't speak DOM or JavaScript.)

Below is some skeleton code.  The elapsed time in milliseconds is EndTime - 
BeginTime.

Paul
______________________________

<form name="SurveyForm" id="SurveyForm" action="...">
         <input type="hidden" name="BeginTime" id="BeginTime" value="" />
         <input type="hidden" name="EndTime" id="EndTime" value="" />
</form>


window.onload = StartTimer

function StartTimer()
{
                 if (!document.getElementById)
                 {
                         alert("Sorry, this survery requires a more modern 
browser"
                         return
                 }

         // time-stamp hidden field
         TimestampHiddenField("BeginTime")

         // set the onsubmit event
         var oForm = document.getElementById("SurveyForm")
         oForm.onsubmit = StopTimer
}

function StopTimer()
{
         // time-stamp hidden field
         TimestampHiddenField("EndTime")

         // submit the form
         return true
}

function TimestampHiddenField(argId)
{
         var oField = document.getElementById(argId)
         var dNow = new Date()
         oField.value = dNow.getTime()
}