一个简易时钟效果js实现代码

var canvas = document.getElementById("clock");var clock = canvas.getContext("2d"); function zhong() { clock.save(); //开始画外层圆 clock.translate(200, 200); clock.strokeStyle = 'black'; clock.lineWidth = 3; clock.beginPath(); clock.arc(0, 0, 195, 0, 2 * Math.PI); clock.stroke(); //时钟上的数字 var shuzi = [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1, 2]; clock.font = "30px Arial"; clock.textAlign = "center"; clock.textBaseline = "middle"; shuzi.forEach(function(number, i) {  var rad = 2 * Math.PI / 12 * i;  var x = Math.cos(rad) * 180;  var y = Math.sin(rad) * 180;  clock.fillText(number, x, y); }); // 小圆点 for(j = 0; j < 60; j++) {  var h = 2 * Math.PI / 60 * j;  var m = Math.cos(h) * 180;  var n = Math.sin(h) * 180;  clock.fillStyle = 'black';  clock.beginPath();  if(j % 5 === 0) {   continue;  }  clock.arc(m, n, 3, 0, 2 * Math.PI);  clock.fill(); }}function drawHour(hour,min) { clock.save(); var rad = 2 * Math.PI / 12 * hour; var red = 2 *Math.PI/12/60*min; clock.rotate(rad+red); clock.lineWidth = 10; clock.lineCap = "round"; clock.beginPath(); clock.moveTo(0, 5); clock.lineTo(0, -100); clock.stroke(); clock.restore();}function drawmin(min) { clock.save(); var rad = 2 * Math.PI / 60 * min; clock.rotate(rad); clock.lineWidth = 5; clock.lineCap = "round"; clock.beginPath(); clock.moveTo(0, 10); clock.lineTo(0, -150); clock.stroke(); clock.restore();}function drawsec(sec) { clock.save(); var rad = 2 * Math.PI / 60 * sec; clock.rotate(rad); clock.lineWidth = 2; clock.lineCap = "round"; clock.strokeStyle = "red"; clock.beginPath(); clock.moveTo(0, 10); clock.lineTo(0, -180); clock.stroke(); clock.restore();}function dian() { clock.fillStyle = "white"; clock.beginPath(); clock.arc(0, 0, 2, 0, 2 * Math.PI); clock.fill();}function xuanzhuan() { clock.clearRect(0,0,400,400); zhong(); var now = new Date(); var hour = now.getHours(); var min = now.getMinutes(); var sec = now.getSeconds(); drawHour(hour,min); drawmin(min); drawsec(sec); dian(); clock.restore();}xuanzhuan();setInterval(xuanzhuan, 1000);