How to make countdown start after clicking a button using local storage

if(localStorage.getItem("total_seconds")){
    var total_seconds = localStorage.getItem("total_seconds");
} 
else {
        var total_seconds = 6*10;
} 
var minutes = parseInt(total_seconds/60);
var seconds = parseInt(total_seconds%60);

function countDownTimer(){
    if(seconds < 10){
        seconds= "0"+ seconds ;
    }
    if(minutes < 10){
        minutes= "0"+ minutes ;
} 
document.getElementById("quiz-time-left").innerHTML = "Time Left :"+minutes+"minutes"+seconds+"seconds";
    if(total_seconds <= 0){
        setTimeout("document.quiz.submit()",1);
        
    } else {
        total_seconds = total_seconds -1 ;
        minutes = parseInt(total_seconds/60);
        seconds = parseInt(total_seconds%60);
        localStorage.setItem("total_seconds",total_seconds)
        setTimeout("countDownTimer()",1000);
} 
} 
setTimeout("countDownTimer()",1000);

Here is the countdown code I copied, I want this counter to start after button is clicked but I can’t seem to succed I couldn’t find a way to put the onclick working function would be good if I could receive some suggestions and tips