这是一款jQuery结合html5 canvas随机生成彩色数字英文组合验证码，不区分字母大小写，提交时判断输入验证码是否正确，点击或刷新随机换一组新的验证码。

使用方法

在页面引入以下jquery.min.js文件

<script type="text/javascript" src="js/jquery.min.js"></script>

<script type="text/javascript">
$(function(){
var show_num = [];
draw(show_num);
   
$("#canvas").on('click',function(){
    draw(show_num);
})
$(".btn").on('click',function(){
    var val = $(".input-val").val().toLowerCase();
    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('');
        draw(show_num);
   
    }else{
        alert('验证码错误！请重新输入！');
        $(".input-val").val('');
        draw(show_num);
    }
})
})
   
function draw(show_num) {
var canvas_width=$('#canvas').width();
var canvas_height=$('#canvas').height();
var canvas = document.getElementById("canvas");//获取到canvas的对象，演员
var context = canvas.getContext("2d");//获取到canvas画图的环境，演员表演的舞台
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,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 <= 3; i++) {
    var j = Math.floor(Math.random() * aLength);//获取到随机的索引值
    var deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度
    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 23px 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 <= 30; i++) { //验证码上显示小点
    context.strokeStyle = randomColor();
    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>

Html结构

在页面引入以下<div>代码部分

<div class="code">
<input type="text" value="" placeholder="请输入验证码（不区分大小写）" class="input-val" />
<canvas id="canvas" width="100" height="43"></canvas>
<button class="btn">提交</button>
</div>