Interval Timers And The Value Of Them - Get -1 As The Output When ValueOf() The Variable

Here is a bit of a conundrum, it you have an interval timer and it is interrupted say by a clearInterval call, how can you tell how far along the interval the timer was when it was canceled? When I look at an object that is an setInterval() event timer, I get -1 as the output when I valueOf() the variable. What I am wondering is if for example the following

Code:
var thisIntervalTimer = setInterval("onceAminute()",60000); the interval of one minute passes between updates, apart from setting up a tracking variable to track milliseconds, does the thisIntervalTimer possess any user accessible values like thisIntervalTimer.getMilliseconds; to return the current 'tick' value of the interval timer attached to the variable thisIntervalTimer. What I would be interested in is if any method exists to access any properties of this object, they must exist in some form as how would the browser know what event timer to update or trigger.