Javascript multiple quiz with a timer

[kirara]

Hi,

I am new to javascript and I want to construct a quiz with five questions, and for each question there is a 3 choises, the user can only choose one answer (radio buttons) and for question there is only a 20 second to answer it before moving to the next question.

my question is, how can I add a timer for each question and move to the next question when the time is 0,

please I'll appreciate any help here :)

[kirara]

here my thoughts:

//array of questions
q = new Array()

//array of answers
a = new Array()
//submitedAnswers
aS = new Array()

//timelimit of each question
timeL = 20;

//score
score =0;
// function to calculate the time
function time(){
}

//function to check the submited answers against the a array

function chechA(){
count =0;
for(count=0, count<q.length,count++){
if(a[count]==aS[count]){
score++
}else{
score --
}

//to go to the next window
function goNext(){
if(timeL==0)
window.history.forward();
}

}

those are my thoughts although I know they miss a lot of things...so any help