Javascript count up asp.net

[JIPedro]

I have been trying to find this solution online, but no luck so far. I need a simple JavaScript code (HH:MM:SS) that count seconds up. I have an asp.net c# web application. I want to run that count on the page load. What JavaScript should be capable of doing is:When it reaches 2 min, change the background of the timer to yellow.When it reaches 4 min, change the background of the timer to red.When it reaches 10 min, play .mp3 or wav file.Can anybody point to right direction?It doesn't necessarily have to be done in JavaScript. If I can do it in c# asp.net that's fine with me.Thank you