页面代码：（使用到了mui样式）
<!DOCTYPE html><html> ???<head> ???????<meta charset="UTF-8"> ???????<meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" /> ???????<meta http-equiv="Pragma" content="no-cache" /> ???????<meta http-equiv="Expires" content="0" /> ???????<meta name="viewport" content="width=device-width, initial-scale=1,maximum-scale=1,user-scalable=no"> ???????<meta name="apple-mobile-web-app-capable" content="yes"> ???????<meta name="apple-mobile-web-app-status-bar-style" content="black"> ???????<title>验证码生成示例</title> ???????<link rel="stylesheet" href="../css/mui/mui.min.css" /> ???????<style> ???????????/*验证码*/ ???????????.verificationCode{ ???????????????width: 4rem; ???????????????height: 100%; ???????????????position: absolute; ???????????????right: 0; ???????????} ???????????canvas{ ???????????????width: 100%; ???????????????height: 100%; ???????????} ???????????#code_img { ???????????????width: 100%; ???????????????height: 100%; ???????????????cursor: pointer; ???????????????vertical-align: top; ???????????} ???????</style> ???</head> ???<body> ???????<div class="mui-content"> ???????????<div class="mui-input-row login_input"> ???????????????<label>验证码</label> ???????????????<input type="text" id="verifital_input" class="mui-input" placeholder="请输入验证码"> ???????????????<div id="verificationCode" class="verificationCode"> ???????????????????<canvas width="100" height="40" id="verifyCanvas"></canvas> ???????????????????<img id="code_img"> ???????????????</div> ???????????</div> ???????</div> ???</body> ???<script type="text/javascript" src="../js/mui/mui.js" ></script> ???<script type="text/javascript" src="../js/jquery-3.3.1.min.js" ></script> ???<script type="text/javascript" src="verificationCode.js" ></script> ???<script> ???????console.log(verVal) ???</script></html>verificationCode.js代码：
var nums = ["1", "2", "3", "4", "5", "6", "7", "8", "9", "0", ????‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘, ‘G‘, ‘H‘, ‘I‘, ‘J‘, ‘K‘, ‘L‘, ‘M‘, ‘N‘, ‘O‘, ‘P‘, ‘Q‘, ‘R‘, ‘S‘, ‘T‘, ‘U‘, ‘V‘, ‘W‘, ‘X‘, ‘Y‘, ‘Z‘, ????‘a‘, ‘b‘, ‘c‘, ‘d‘, ‘e‘, ‘f‘, ‘g‘, ‘h‘, ‘i‘, ‘j‘, ‘k‘, ‘l‘, ‘m‘, ‘n‘, ‘o‘, ‘p‘, ‘q‘, ‘r‘, ‘s‘, ‘t‘, ‘u‘, ‘v‘, ‘w‘, ‘x‘, ‘y‘, ‘z‘];var str = ‘‘;var verVal = drawCode();// 绘制验证码function drawCode (str) { ???var canvas = document.getElementById("verifyCanvas"); //获取HTML端画布 ???var context = canvas.getContext("2d"); //获取画布2D上下文 ???context.fillStyle = "cornflowerblue"; //画布填充色 ???context.fillRect(0, 0, canvas.width, canvas.height); //清空画布 ???context.fillStyle = "white"; //设置字体颜色 ???context.font = "25px Arial"; //设置字体 ???var rand = new Array(); ???var x = new Array(); ???var y = new Array(); ???for (var i = 0; i < 4; i++) { ???????rand.push(rand[i]); ???????rand[i] = nums[Math.floor(Math.random() * nums.length)] ???????x[i] = i * 20 + 10; ???????y[i] = Math.random() * 20 + 20; ???????context.fillText(rand[i], x[i], y[i]); ???} ???str = rand.join(‘‘).toUpperCase(); ???//画3条随机线 ???for (var i = 0; i < 3; i++) { ???????drawline(canvas, context); ???} ???// 画30个随机点 ???for (var i = 0; i < 30; i++) { ???????drawDot(canvas, context); ???} ???convertCanvasToImage(canvas); ???return str;}// 随机线function drawline (canvas, context) { ???context.moveTo(Math.floor(Math.random() * canvas.width), Math.floor(Math.random() * canvas.height)); //随机线的起点x坐标是画布x坐标0位置，y坐标是画布高度的随机数 ???context.lineTo(Math.floor(Math.random() * canvas.width), Math.floor(Math.random() * canvas.height)); //随机线的终点x坐标是画布宽度，y坐标是画布高度的随机数 ???context.lineWidth = 0.5; //随机线宽 ???context.strokeStyle = ‘rgba(50,50,50,0.3)‘; //随机线描边属性 ???context.stroke(); //描边，即起点描到终点}// 随机点(所谓画点其实就是画1px像素的线，方法不再赘述)function drawDot (canvas, context) { ???var px = Math.floor(Math.random() * canvas.width); ???var py = Math.floor(Math.random() * canvas.height); ???context.moveTo(px, py); ???context.lineTo(px + 1, py + 1); ???context.lineWidth = 0.2; ???context.stroke();}// 绘制图片function convertCanvasToImage (canvas) { ???document.getElementById("verifyCanvas").style.display = "none"; ???var image = document.getElementById("code_img"); ???image.src = canvas.toDataURL("image/png"); ???return image;}// 点击图片刷新document.getElementById(‘code_img‘).onclick = function() { ???resetCode();}function resetCode () { ???$(‘#verifyCanvas‘).remove(); ???$(‘#code_img‘).before(‘<canvas width="100" height="40" id="verifyCanvas"></canvas>‘) ???verVal = drawCode();}js生成图片验证码
原文地址：https://www.cnblogs.com/zh-1721342390/p/9370794.html