var dom = document.getElementById('clock');
var ctx = dom.getContext('2d');
var width = ctx.canvas.width;
var height = ctx.canvas.height;
function drawBackground() {
ctx.arc(0, 0, r - ctx.lineWidth /2, 0, 2 * Math.PI, false);
var hourNumbers = [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1, 2];
ctx.font = 18*rem+"px Arial";
ctx.textAlign = "center";
ctx.textBaseline = "middle";
hourNumbers.forEach(function(number, i) {
var rad = 2 * Math.PI / 12 * i;
var x = Math.cos(rad) * (r - 30*rem);
var y = Math.sin(rad) * (r - 30*rem);
ctx.fillText(number, x, y);
for (var i = 0; i < 60; i++) {
var rad = 2 * Math.PI / 60 * i;
var x = Math.cos(rad) * (r - 18*rem);
var y = Math.sin(rad) * (r - 18*rem);
ctx.arc(x, y, 2*rem, 0, 2 * Math.PI, false);
ctx.arc(x, y, 2*rem, 0, 2 * Math.PI, false);
function drawHour(hour, minute) {
var rad = 2 * Math.PI / 12 * hour;
var mrad = 2 * Math.PI / 12 / 60 * minute;
function drawMinute(minute) {
var rad = 2 * Math.PI / 60 * minute;
ctx.lineTo(0, -r + 30*rem);
function drawSecond(second) {
var rad = 2 * Math.PI / 60 * second;
ctx.moveTo(-2*rem, 20*rem);
ctx.lineTo(2*rem, 20*rem);
ctx.lineTo(1, -r + 16*rem);
ctx.lineTo(-1, -r + 16*rem);
ctx.arc(0, 0, 3*rem, 0, 2 * Math.PI, false);
ctx.clearRect(0, 0, width, height);
var hour = now.getHours();
var minute = now.getMinutes();
var second = now.getSeconds();
setInterval(draw01, 1000);