今天要來分享我看 Youtube 影片做出來的 timer，
照慣例先放影片連結，
用他裡面提到的觀念延伸做出我這個 timer。

HTML

<div class="timer">
  <div class="time">
    <span id="minute">00</span>:<span id="second">00</span>
  </div>
  <svg width="300" height="300">
    <circle id="circle1" cx="150" cy="150" r="120"></circle>
    <circle id="circle2" cx="150" cy="150" r="120"></circle>
  </svg>
</div>
<button id="button">START</button>
<button id="reset">RESET</button>

CSS

@import url('https://fonts.googleapis.com/css2?family=Space+Mono:wght@400;700&display=swap');

*{
  margin: 0;
  padding: 0;
  list-style:none;
  line-height: 1;
  box-sizing: border-box;
}
body{
  background-color: #1b262c;
  text-align:center;
  font-family: 'Space Mono', monospace;
}

.timer{
  position: relative;
}

.time {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%)
}

.time{
  font-size: 40px;
  color: #fff;
}

svg{
  display: inline-block;
  vertical-align: middle;
}
circle{
  stroke-width: 5px;
  fill: transparent;
  stroke-linecap: round;
}

#circle1{
  stroke: rgba(0,0,0, .4);
}

#circle2{
  stroke:#bbe1fa;
  transition: 1s linear;
}

button{
  vertical-align: middle;
  width: 80px;
  padding: 10px;
  margin: 0;
  color: #fff;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  font-family: 'Space Mono', monospace;
}

button:focus{
  outline:none;
}

button:active{
  box-shadow: inset 0px 0px 1px 2px #1b262c;
}

#button{
  background-color: #0f4c75;
}

#reset{
  background-color: #3282b8;
}

JS

const circle = document.getElementById('circle2');
const button = document.getElementById('button');
const reset = document.getElementById('reset')
const length = circle.getTotalLength();
const minute = document.getElementById('minute');
const second = document.getElementById('second');

circle.style.strokeDasharray = length;
circle.style.strokeDashoffset = length;

let count = 0;
let timer;
let isPlaying = false;

button.addEventListener('click', 
  function() {
  isPlaying = !isPlaying;
  if(isPlaying){
    startTimer();
  }else{
    stopTimer();
  }
}
);

reset.addEventListener('click', resetTimer);

function startTimer(){
  button.textContent = "STOP";
  timer = setInterval(function(){
    count++;
    minute.textContent = (Math.floor(count / 60) < 10 ? '0' : '') + Math.floor(count / 60) ;
    second.textContent = (count % 60 < 10 ? '0' : '') + count % 60 ;
    circle.style.strokeDashoffset = length - (count / 60) * length;
  },1000)
}
  
function stopTimer(){
    console.log('stopTimer');
    clearInterval(timer);
    button.textContent = "START";
  }

function resetTimer(){
  stopTimer();
  count = 0;
  minute.textContent = '00';
  second.textContent = '00'
  circle.style.strokeDashoffset = length;
  isPlaying = false;
}

也直接附上我的 codepen，
今天就先到這裡啦～
我們明天見。