JS html时钟制作代码分享

时钟效果图：

闲来无聊做了一个网页的时钟，效果模拟传统时钟的运行方式，

运用了html 的画布实现指针，背景图片引用了网络图片。

具体原理：

首先将时钟分为四个不同区域，对每个区域计算cos，sin 来确实指针顶点位置。在通过画布来绘画出指针。
通过setInterval 每秒刷新指针位置实现 传统机械表针的动态跳动。

本人是JS开发程序员，从业1年多。闲来无聊的简单页面，

欢迎大家提问，或者建议。共同进步

代码部分，直接复制HTML 文件中即可查看效果：

<!DOCTYPE html>
<html>
<head>
  <meta charset=utf-8>
  <title>clock</title>
</head>
<body style="color:green; <!--background-image:url('http://image.lxway.com/upload/b/f0/bf0d97dcee487096548e6edbc89d4963_thumb.png');--> background-size:100%; background-repeat: no-repeat; background-attachment:fixed">
  <div style="width: 900px; height: 900px; margin-top: 50px; margin-left: 50px;">
    <div style="position: absolute; left:119px;top: 193px; width: 900px; height: 900px; background-image:url('http://image.lxway.com/upload/b/f0/bf0d97dcee487096548e6edbc89d4963_thumb.png'); background-repeat: no-repeat; z-index: -1;">
    </div>
    <canvas id="t" width="800" height="800"></canvas>
    <div style="position: absolute; left:118px;top: 464px; width: 100px; height: 200px; background-color: white; background-repeat: no-repeat; z-index: 10;">
    </div>
  </div>
  <script language="javascript">
        var s = setInterval(moveI, 1000);
        function moveI() {
          var c = document.getElementById("t");
          var pc = c.getContext("2d");
          c.height = c.height;
          //秒
          pc.lineWidth = 3;
          pc.strokeStyle = 'rgba(255,0,0,0.8)';
          var now = new Date();
          var sindex = getxy(150, now.getSeconds());
          pc.moveTo(400, 400);
          pc.lineTo(sindex.x, sindex.y);
          pc.stroke();
          pc.beginPath();
          //分
          pc.lineWidth = 7;
          pc.strokeStyle = 'rgba(50,50,50,0.8)';
          var mindex = getxy(120, now.getMinutes() + (now.getSeconds() / 60));
          pc.moveTo(400, 400);
          pc.lineTo(mindex.x, mindex.y);
          pc.stroke();
          pc.beginPath();
          //时
          pc.lineWidth = 10;
          pc.strokeStyle = 'rgba(0,0,0,0.8)';
          var hindex = getxy(80, ((now.getHours() > 12 ? now.getHours() - 12 : now.getHours()) + (now.getMinutes() / 60)) * 5);
          pc.moveTo(400, 400);
          pc.lineTo(hindex.x, hindex.y);
          pc.stroke();
        };

        function getxy(r, t) {
          //计算分区 0,1,2,3
          var a = parseInt(t / 15);
          //分区角度
          t = t - 15 * a;
          var y;
          var x;
          //基于分区的坐标计算
          switch (a) {
            case 0:
              y = r - (r * Math.cos(2 * Math.PI / 360 * 90 * (t / 15)));
              x = r + (r * Math.sin(2 * Math.PI / 360 * 90 * (t / 15)));
              break;
            case 1:
              y = r + (r * Math.sin(2 * Math.PI / 360 * 90 * (t / 15)));
              x = r + (r * Math.cos(2 * Math.PI / 360 * 90 * (t / 15)));
              break;
            case 2:
              y = r + (r * Math.cos(2 * Math.PI / 360 * 90 * (t / 15)));
              x = r - (r * Math.sin(2 * Math.PI / 360 * 90 * (t / 15)));
              break;
            case 3:
              y = r - (r * Math.sin(2 * Math.PI / 360 * 90 * (t / 15)));
              x = r - (r * Math.cos(2 * Math.PI / 360 * 90 * (t / 15)));
              break;
            default:
              break;
          }
          y = (400 - r) + y;
          x = (400 - r) + x;
          return {
            'x': x,
            'y': y
          };
        };
  </script>
</body>

</html>

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