javascript.js

let m = 0;
let s = 0;
let ms = 0;

let timer;

let stopwatchEl = document.querySelector('.stopwatch');
let lapsContainer = document.querySelector('.laps');

function start(){
    console.log(!timer);
    if(!timer){ //so if you press start button many times, there wont be a glitch
        timer = setInterval(run , 10);
    }
}

function run(){
    stopwatchEl.textContent = getTimer();
    ms++;
    if(ms === 100){
        ms = 0;
        s++;
    }
    if(s === 60){
        s = 0;
        m++;
    }
}

function pause(){
    stopTimer();
}

function stop(){
    stopTimer();
    m = 0;
    s = 0;
    ms = 0;
    stopwatchEl.textContent = getTimer();
}

function stopTimer(){
    clearInterval(timer);
    timer = false;
}

function getTimer(){
    return (m < 10 ? "0" + m : m) + ":" + (s < 10 ? "0" + s : s) + ":" + (ms < 10 ? "0" + ms : ms);
}

function restart(){
    stop();
    start();
}

function lap() {
    if(timer){
        let li = document.createElement("li");
        li.innerText = getTimer();
        lapsContainer.appendChild(li);
    }
}

function resetLaps(){
    lapsContainer.innerHTML = "";
}