<!DOCTYPE html><html><head> <meta name="viewport" content="width=device-width,initial-scale=1"> <title>canvas时钟</title> <style type="text/css"> div { text-align: center; margin-top: 250px; } #clock { border: 1px solid #ccc; } </style></head><body> <div> <canvas id="clock" height="200px" width="200px"></canvas> </div> <script type="text/javascript" src="clock.js"></script></body></html>var dom = document.getElementById('clock');var ctx = dom.getContext('2d');var width = ctx.canvas.width;var height = ctx.canvas.height;var r = width / 2;var rem = width / 200;function drawBackground(){ ctx.save(); ctx.translate(r,r); ctx.beginPath(); ctx.lineWidth = 10 * rem; ctx.arc(0,0,r - ctx.lineWidth / 2,0,2 * Math.PI,false); ctx.stroke(); 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 = Matn.cos(rad) * (r - 30 * rem); var y = Matn.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 = Matn.cos(rad) * (r - 18 * rem); var y = Matn.sin(rad) * (r - 18 * rem); ctx.beginPath(); if (i % 5 === 0){ ctx.fillStyle = '#000'; ctx.arc(x,y,2 * rem,0,2 * Math.PI,false); }else{ ctx.fillStyle = '#ccc'; ctx.arc(x,y,2 * rem,0,2 * Math.PI,false); } ctx.fill(); }}function drawHour(hour,minute){ ctx.beginPath(); var rad = 2 * Math.PI / 12 * hour; var mrad = 2 * Math.PI / 12 / 60 * minute; ctx.rotate(rad + mrad); ctx.lineWidth = 6 * rem; ctx.lineCap = 'round'; ctx.moveTo(0,10 * rem); ctx.lineTo(0,-r / 2); ctx.stroke();}function drawMinute(minute){ ctx.save(); ctx.beginPath(); var rad = 2 * Math.PI / 60 * minute; ctx.rotate(rad); ctx.lineWidth = 3 * rem; ctx.lineCap = 'round'; ctx.moveTo(0,10 * rem); ctx.lineTo(0,-r + 30 * rem); ctx.stroke(); ctx.restore(); }function drawSecond(second){ ctx.save(); ctx.beginPath(); ctx.fillStyle='#c14543'; var rad = 2 * Math.PI / 60 * second; ctx.rotate(rad); ctx.moveTo(-2 * rem,20 * rem); ctx.lineTo(2 * rem,20 * rem); ctx.lineTo(1,-r + 18 * rem); ctx.lineTo(-1,-r + 18 * rem); ctx.fill(); ctx.restore(); }function drawDot(){ ctx.beginPath(); ctx.fillStyle='#fff'; ctx.arc(0,0,3 * rem,0,2 * Math.PI,false);}drawBackground();drawDot();function draw(){ ctx.clearRect(0,0,width,height); var now = new Date(); var hour = now.getHours(); var minute = now.getMinutes(); var second = now.getSeconds(); drawBackground(); drawHour(hour,minute); drawMinute(minute); drawSecond(second); drawDot(); ctx.restore();}setInterval(draw,1000)按F12打开浏览器的开发者工具，就能看到报错，你把“Math”写成“Matn”了