用Canvas绘制一个钟表

效果图：
<html>
<head></head>
<body>
<canvas id="canvas1"height="500px"width="500px">您的浏览器不支持canvas标签。</canvas>
<script>
var c=document.getElementById("canvas1");
var clock=c.getContext("2d");
function drawclock(){
    //清除画布，每画一次就要清除上一次的
    clock.clearRect(0,0,500,500);
    var now=new Date();
    var sec=now.getSeconds();
    var min=now.getMinutes();
    var hour=now.getHours();

    //小时必须获取浮点类型（小时+分钟转换成的小时）
    hour=hour+min/60;
    //获取的时间为24小时的（），需要转换为12小时的（小时）
    hour=hour>12?hour-12:hour;//hour是否大于12，如果大于则hour=hour-12否则hour=hour。

    //表盘
    clock.lineWidth=10;
    clock.strokeStyle="#41216e";
    clock.beginPath();
    clock.arc(250,250,100,0,360,false);
    clock.closePath();
    clock.stroke();
    //时刻度,12个，所以用for循环来画
    for(var i=0;i<12;i++){
        clock.save();
        clock.lineWidth=6;
        clock.strokeStyle="#6f3a81";
        //先设置（0，0）点
        clock.translate(250,250);
        //再设置旋转角度
        clock.rotate(i*30*Math.PI/180);
        clock.beginPath();
        clock.moveTo(0,-93);
        clock.lineTo(0,-80);
        clock.stroke();
        clock.closePath();
        clock.restore();
    }

    //分刻度
    for(var j=0;j<60;j++){
        clock.save();
        clock.lineWidth=4;
        clock.strokeStyle="#6f3a81";
        clock.translate(250,250);
        clock.rotate(j*6*Math.PI/180);
        clock.beginPath();
        clock.moveTo(0,-93);
        clock.lineTo(0,-85);
        clock.stroke();
        clock.closePath();
        clock.restore();
    }

    //时针
    clock.save();
    clock.lineWidth=6;
    clock.strokeStyle="#170523";
    clock.translate(250,250);
    clock.rotate(hour*30*Math.PI/180);
    clock.beginPath();
    clock.moveTo(0,-40);
    clock.lineTo(0,10);
    clock.lineCap="round";
    clock.closePath();
    clock.stroke();
    clock.restore();

    //分针
    clock.save();
    clock.lineWidth=4;
    clock.strokeStyle="#170523";
    clock.translate(250,250);
    clock.rotate(min*6*Math.PI/180);
    clock.beginPath();
    clock.moveTo(0,-58);
    clock.lineTo(0,15);
    clock.closePath();
    clock.stroke();
    clock.restore();
    //秒针
    clock.save();
    clock.lineWidth=2;
    clock.strokeStyle="#c582ba";
    clock.translate(250,250);
    clock.rotate(sec*6*Math.PI/180);
    clock.beginPath();
    clock.moveTo(-70,0);
    clock.lineTo(16,0);
    clock.stroke();
    clock.closePath();
    //画出时针，分针，秒针的交叉点
    clock.beginPath();
    clock.fillStyle="black";
    clock.arc(0,0,5,0,360);
    clock.arc(-60,0,2.5,0,360);
    clock.fill();
    clock.closePath();
    clock.stroke();
    clock.restore();
}
    //使用setInterval一秒钟调用一次
    setInterval(drawclock,1000);
</body>
</script>

</html>