JQuery canvas 验证码

$(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(); 把大写转换为小写，则验证码不分大小写
            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('');
                draw(show_num);

            }else{
                alert('验证码错误！请重新输入！');
                $(".input-val").val('');
                draw(show_num);
            }
        })
    });

canvas的编辑：

　　完整代码：

<!DOCTYPE html>
<html>

<head>
<meta charset="utf-8" />
<title>canvas 验证码</title>
<style type="text/css">
*{margin:0;padding:0;}
.code input{200px;height:25px;}
.code canvas{border:1px solid red;}
</style>
</head>

<body>
<div class="code">
<input type="text" value="" placeholder="请输入验证码" class="input-val" />
<canvas id="canvas" width="100" height="25"></canvas>
<button class="btn">提交</button>
</div>
<script src="https://code.jquery.com/jquery-3.3.1.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();
//toLowerCase(); 把大写转换为小写，则验证码不分大小写
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('');
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
//验证码的个数在此处设置
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 = "18px 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>
</body>

</html>