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コピペで使えるアナログ時計を表示するWEBサイト(Canvas+Javascript)

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Javascriptでcanvasにアナログ時計を表示させます。
地道にSin、Cosで座標を計算して描画しています。

<canvas id="clock" style="width:200px;height:200px;"></canvas>

<script>
function TAnalogClock(clockCanvas){
  this.can=clockCanvas;
  this.size=200;
  this.can.width=this.size;
  this.can.height=this.size;
  this.ctx=this.can.getContext("2d", {willReadFrequently:true});
  this.ctx.scale(1,1);
  this.ctx.lineCap='round';
  this.draw=function(){
    //現在時分秒の取得
    let jikan=new Date();
    let hour=jikan.getHours();
    let minute=jikan.getMinutes();
    let second=jikan.getSeconds();
    let ms=jikan.getMilliseconds();
    //キャンバスのクリア
    this.ctx.clearRect(0,0,this.size,this.size);
    let r=this.size/2;
    //円の描画
    this.ctx.beginPath();
    this.ctx.strokeStyle="rgb(0,0,0)";
    this.ctx.lineWidth=r/12;
    this.ctx.arc(r,r,r*0.9,0,Math.PI*2,false);
    this.ctx.stroke();

    //5分毎の目盛りの描画
    for(i=0;i<=60;i+=5){
      this.ctx.beginPath();
      this.ctx.strokeStyle="rgb(0,0,0)";
      this.ctx.lineWidth=r/12;
      this.ctx.moveTo(r+Math.cos(i/30*Math.PI)*r*0.9 ,
        r+Math.sin(i/30*Math.PI)*r*0.9 );
      this.ctx.lineTo(r+Math.cos(i/30*Math.PI)*r*0.82,
        r+Math.sin(i/30*Math.PI)*r*0.82);
      this.ctx.stroke();
    }
    //短針
    this.ctx.beginPath();
    this.ctx.strokeStyle="rgb(60,60,60)";
    this.ctx.lineWidth=r/6;
    this.ctx.moveTo(r,r);
    this.ctx.lineTo(r+Math.cos((hour+minute/60-3)/6*Math.PI)*r*0.56,
      r+Math.sin((hour+minute/60-3)/6*Math.PI)*r*0.56);
    this.ctx.stroke();
    //長針
    this.ctx.beginPath();
    this.ctx.strokeStyle="rgb(0,0,0)";
    this.ctx.lineWidth=r/10;
    this.ctx.moveTo(r,r);
    this.ctx.lineTo(r+Math.cos((minute-15)/30*Math.PI)*r*0.7,
      r+Math.sin((minute-15)/30*Math.PI)*r*0.7);
    this.ctx.stroke();
    //秒針
    this.ctx.beginPath();
    this.ctx.strokeStyle="rgb(120,120,120)";
    this.ctx.lineWidth=r/16;
    this.ctx.moveTo(r,r);
    this.ctx.lineTo(r+Math.cos((second+ms/1000-15)/30*Math.PI)*r*0.76,
      r+Math.sin((second+ms/1000-15)/30*Math.PI)*r*0.76);
    this.ctx.stroke();
  }
  setInterval(this.draw.bind(this),100);
}
window.addEventListener("DOMContentLoaded",function(){
  //コンストラクタにアナログ時計を描画するキャンバスを指定する
  AnalogClock=new TAnalogClock(document.querySelector("#clock"));
});
</script>