以下是完整代码，保存到html文件可以查看效果。

HTML5时钟-柯乐义

柯乐义 原文

HTML5时钟

柯乐义提示您，请使用支持HTML5的浏览器，例如Chrome,IE9,IE10,Firefox等。

var canvas = document.getElementById('canvas');

var ctx = canvas.getContext('2d');

if (ctx) {

var timerId;

var frameRate = 60;

function canvObject() {

this.x = 0;

this.y = 0;

this.rotation = 0;

this.borderWidth = 2;

this.borderColor = '#000000';

this.fill = false;

this.fillColor = '#ff0000';

this.update = function () {

if (!this.ctx) throw new Error('柯乐义提示：您没指定ctx对象。');

var ctx = this.ctx

ctx.save();

ctx.lineWidth = this.borderWidth;

ctx.strokeStyle = this.borderColor;

ctx.fillStyle = this.fillColor;

ctx.translate(this.x, this.y);

if (this.rotation) ctx.rotate(this.rotation * Math.PI / 180);

if (this.draw) this.draw(ctx);

if (this.fill) ctx.fill();

ctx.stroke();

ctx.restore();

}

};

function Line() { };

Line.prototype = new canvObject();

Line.prototype.fill = false;

Line.prototype.start = [0, 0];

Line.prototype.end = [5, 5];

Line.prototype.draw = function (ctx) {

ctx.beginPath();

ctx.moveTo.apply(ctx, this.start);

ctx.lineTo.apply(ctx, this.end);

ctx.closePath();

};

function Circle() { };

Circle.prototype = new canvObject();

Circle.prototype.draw = function (ctx) {

ctx.beginPath();

ctx.arc(0, 0, this.radius, 0, 2 * Math.PI, true);

ctx.closePath();

};

var circle = new Circle();

circle.ctx = ctx;

circle.x = 100;

circle.y = 100;

circle.radius = 90;

circle.fill = true;

circle.borderWidth = 6;

circle.fillColor = '#ffffff';

var hour = new Line();

hour.ctx = ctx;

hour.x = 100;

hour.y = 100;

hour.borderColor = "#000000";

hour.borderWidth = 10;

hour.rotation = 0;

hour.start = [0, 20];

hour.end = [0, -50];

var minute = new Line();

minute.ctx = ctx;

minute.x = 100;

minute.y = 100;

minute.borderColor = "#333333";

minute.borderWidth = 7;

minute.rotation = 0;

minute.start = [0, 20];

minute.end = [0, -70];

var seconds = new Line();

seconds.ctx = ctx;

seconds.x = 100;

seconds.y = 100;

seconds.borderColor = "#ff0000";

seconds.borderWidth = 4;

seconds.rotation = 0;

seconds.start = [0, 20];

seconds.end = [0, -80];

var center = new Circle();

center.ctx = ctx;

center.x = 100;

center.y = 100;

center.radius = 5;

center.fill = true;

center.borderColor = 'orange';

for (var i = 0, ls = [], cache; i < 12; i++) {

cache = ls[i] = new Line();

cache.ctx = ctx;

cache.x = 100;

cache.y = 100;

cache.borderColor = "orange";

cache.borderWidth = 2;

cache.rotation = i * 30;

cache.start = [0, -70];

cache.end = [0, -80];

}

timerId = setInterval(function () {

// 清除画布

ctx.clearRect(0, 0, 200, 200);

// 填充背景色

ctx.fillStyle = 'orange';

ctx.fillRect(0, 0, 200, 200);

// 表盘

circle.update();

// 刻度

for (var i = 0; cache = ls[i++]; ) cache.update();

// 时针

hour.rotation = (new Date()).getHours() * 30;

hour.update();

// 分针

minute.rotation = (new Date()).getMinutes() * 6;

minute.update();

// 秒针

seconds.rotation = (new Date()).getSeconds() * 6;

seconds.update();

// 中心圆

center.update();

}, (1000 / frameRate) | 0);

} else {

alert('柯乐义提示：您的浏览器不支持HTML5无法预览.');

}