To initalize the variable only once, while starting the project in javascript

Hello frnd! I require to initalize a variable in javascript only at the time of running the project which i have written in aspx page in asp.net(c#). I am making a timer, and that timer needs to note the current time (hh:mm:ss) bt as soon page gets refresh or postback , the timer's starting time is reinitalized........... i need to stop the timer being reinalized ............... pls help me its urgent.............. Thanx.....