使用路径arc-七彩

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>使用路径</title>
</head>
<body>
    <canvas id="ourCanvas" width="450" height="450" style="border:3px dashed #000;" ></canvas>
<script>
    //arc(float x,float y,float radius,float startAngel,endAngel,booleancounterclockwise)counterclockwise逆时针
    //向Canvas的当前路径添加一段弧。绘制以x、y为圆心的，radius为半径，从startAngel角度开始，到endAngel角度结束的圆弧。startAngel和endAngel以弧度作为单位。
    //true表示逆时针，false表示顺时针
    var canvas = document.getElementById("ourCanvas");
    var ctx = canvas.getContext("2d");

ctx.beginPath();
        ctx.arc(120, 120,100, 0,120, true);
        ctx.closePath();
        ctx.strokeStyle = "#f00";
        ctx.lineWidth = 20;
        ctx.shadowBlur =15;
        ctx.shadowColor = "#ff0";
        ctx.shadowOffsetX = 7;
        ctx.shadowOffsetY = 7;
        ctx.stroke();

//for (var i = 0; i < 10; i++) {
    //    ctx.beginPath();
    //    ctx.arc(i * 33, i * 33, (i + 1) * 10, 0, Math.PI * 2, true);
    //    ctx.closePath();
    //    ctx.fillStyle = 'rgba(155,201,93,' + (10 - i) * 0.1 + ')';
    //    ctx.fill();
    //}
</script>
</body>
</html>