这篇文章主要介绍JS怎么实现验证码，文中介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们一定要看完！
具体代码：
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>验证码 - 编程网(yisu.com)</title> <style> .input-val { width: 150px; height: 30px; border: 1px solid #ddd; box-sizing: border-box; } #canvas { vertical-align: middle; box-sizing: border-box; border: 1px solid #ddd; cursor: pointer; } .btn { display: block; margin-top: 10px; height: 30px; width: 80px; font-size: 16px; color: #fff; background-color: #409EFE; border: 1px solid #EBEDEF; border-radius: 50px; } </style></head><script type="text/javascript" src="https://libs.baidu.com/jquery/2.1.4/jquery.min.js" ></script><script> $(function(){ var show_num = []; draw(show_num); $("#canvas").on('click',function(){ draw(show_num); }) $(".btn").on('click',function(){ var val = $(".input-val").val().toLowerCase(); //toLowerCase()函数将字符串中的所有字符转为小写。所以输入框不区分大小写。 var num = show_num.join(""); if(val==''){ alert('请输入验证码！'); }else if(val == num){ alert('提交成功！'); $(".input-val").val(''); }else{ alert('验证码错误！请重新输入！'); $(".input-val").val(''); } }) }) function draw(show_num) {//生成并渲染出验证码图形 var canvas_width=$('#canvas').width(); var canvas_height=$('#canvas').height(); var canvas = document.getElementById("canvas");//获取canvas var context = canvas.getContext("2d");//获取到canvas画图的环境 canvas.width = canvas_width; canvas.height = canvas_height; var sCode = "A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z,1,2,3,4,5,6,7,8,9,0"; var aCode = sCode.split(","); var aLength = aCode.length;//获取到数组的长度 for (var i = 0; i < 4; i++) { //这里的for循环可以控制验证码位数 var j = Math.floor(Math.random() * aLength);//获取到随机的索引值 var deg = Math.random() - 0.5; //产生一个随机弧度 var txt = aCode[j];//得到随机的一个内容 show_num[i] = txt.toLowerCase(); var x = 10 + i * 20;//文字在canvas上的x坐标 var y = 20 + Math.random() * 8;//文字在canvas上的y坐标 context.font = "bold 24px 微软雅黑"; context.translate(x, y); context.rotate(deg); context.fillStyle = randomColor(); context.fillText(txt, 0, 0); context.rotate(-deg); context.translate(-x, -y); } for (var i = 0; i <= 5; i++) { //验证码上显示线条 context.strokeStyle = randomColor(); context.beginPath(); context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height); context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height); context.stroke(); } for (var i = 0; i <= 20; i++) { //验证码上的小点 context.strokeStyle = randomColor();//随机生成 context.beginPath(); var x = Math.random() * canvas_width; var y = Math.random() * canvas_height; context.moveTo(x, y); context.lineTo(x + 1, y + 1); context.stroke(); } } function randomColor() {//得到随机的颜色值 var r = Math.floor(Math.random() * 256); var g = Math.floor(Math.random() * 256); var b = Math.floor(Math.random() * 256); return "rgb(" + r + "," + g + "," + b + ")"; }</script><body> <div class="code"> <input type="text" value="" placeholder="请输入验证码" class="input-val"> <canvas id="canvas" width="100" height="30"></canvas> <button class="btn">验证</button> </div></body></html>以上是“JS怎么实现验证码”这篇文章的所有内容，感谢各位的阅读！希望分享的内容对大家有帮助，更多相关知识，欢迎关注编程网行业资讯频道！
