[F8] Help with adding functions to Timer

Hi,

I need to add some functions to this timer and was wondering how.
code is below

1. when the timer reaches :30 it needs to flash a warning
2. when the timer reaches :00 it needs to display a ending message

thanks

ponyack

Code:

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function countDown() {
        if (Math.round(outputMin)==0 && Math.round(outputSec)==0 || chk==1){
                clearInterval(timer);
        }else {
                if (outputSec != "00") {
                        outputSec = Math.round(outputSec) - 1;
                        //trace(output);
                }else {
                        outputSec = 59;
                        outputMin = Math.round(outputMin) -1;
                }
                if (outputSec <= 9 && outputSec > 0) {
                        outputSec ="0" + outputSec;
       
                }else if (outputSec == 0) {
                        outputSec = "00";
                }
        }
}

chk=0;
stop();

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