<div class="code">
<input type="text" value="" placeholder="請輸入驗證碼" class="input-val" />
<canvas id="canvas" width="100" height="43"></canvas>
<button class="btn">提交</button>
</div>

$(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(); 把大寫轉換為小寫，則驗證碼不分大小寫
var num = show_num.join("");
if(val==‘‘){
alert(‘請輸入驗證碼！‘);
}else if(val == num){
alert(‘提交成功！‘);
$(".input-val").val(‘‘);
draw(show_num);

}else{
alert(‘驗證碼錯誤！請重新輸入！‘);
$(".input-val").val(‘‘);
draw(show_num);
}
})
});

canvas的編輯：

function draw(show_num) {
var canvas_width=$(‘#canvas‘).width();
var canvas_height=$(‘#canvas‘).height();
var canvas = document.getElementById("canvas");//獲取到canvas的對象，演員
var context = canvas.getContext("2d");//獲取到canvas畫圖的環境，演員表演的舞臺
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;//獲取到數組的長度
//驗證碼的個數在此處設置
for (var i = 0; i <= 3; i++) {
var j = Math.floor(Math.random() * aLength);//獲取到隨機的索引值
var deg = Math.random() * 30 * Math.PI / 180;//產生0~30之間的隨機弧度
var txt = aCode[j];//得到隨機的一個內容
show_num[i] = txt.toLowerCase();
var x = 10 + i * 20;//文字在canvas上的x坐標
var y = 20 + Math.random() * 8;//文字在canvas上的y坐標
context.font = "bold 23px 微軟雅黑";

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++) { //驗證碼上顯示線條
// 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++) { //驗證碼上顯示小點
// 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() {//得到隨機的顏色值
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 + ")";
}

JQuery canvas 驗證碼