1,html部分

<div class="box"><label class="side">验证码</label><input class="box-flex input-full" id="verify" type="text" placeholder="请输入验证码" ><div class="side" style="width: 100px;margin-left:10px;"><canvas width="100" height="40" id="verifyCanvas"></canvas><img id="code_img"></div></div>

2，js部分

//下面为验证码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'];drawCode();// 绘制验证码function drawCode() {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 = "#565656";                  //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 < 5; i++) {rand[i] = nums[Math.floor(Math.random() * nums.length)]x[i] = i * 16 + 10;y[i] = Math.random() * 20 + 20;context.fillText(rand[i], x[i], y[i]);}//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)}// 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 () {$('#verifyCanvas').remove();$('#verify').after('<canvas width="100" height="40" id="verifyCanvas"></canvas>');drawCode();}