js驗證碼

時間 2019-11-07

原文原文鏈接

效果圖javascript

原理：draw方法用隨機數的方式在cavs上畫驗證碼，經過事件獲取input框的驗證碼與畫的驗證碼比較css

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
    <style type="text/css">
        *{
            margin:0;
            padding: 0;
            box-sizing: border-box;
        }
        html{
            width: 100%;
            height: 100%;
            font-size: 16px;
        }
        body{
            width: 100%;
            height: 100%;
            -moz-user-select: none; /*火狐*/ /*禁止用戶在頁面選擇文字*/
            -webkit-user-select: none; /*webkit瀏覽器*/
            -ms-user-select: none; /*IE10*/
            -khtml-user-select: none; /*早期瀏覽器*/
            user-select: none;
        }
        .code{
            width: 400px;
            margin:0 auto;
        }
        .input-val{
            width: 295px;
            background: #ffffff;
            height: 2.8rem;
            padding: 0 2%;
            border-radius: 5px;
            border: none;
            border: 1px solid rgba(0,0,0,.2);
            font-size: 1.0625rem;
        }
        #canvas{
            float:right;
            display: inline-block;
            border:1px solid #ccc;
            border-radius: 5px;
            cursor: pointer;
        }
        .btn{
            width: 100px;
            height: 40px;
            background: #f1f1f1;
            border: 1px solid #ccc;
            border-radius: 5px;
            margin: 20px auto 0;
            display: block;
            font-size: 1.2rem;
            color: #e22e1c;
            cursor: pointer;
        }
    </style>
</head>
<body>
    <div class="code">
    	<input type="text" value="" placeholder="請輸入驗證碼（不區分大小寫）" class="input-val" />
        <canvas id="canvas" width="100" height="43"></canvas>
        <button class="btn">提交</button>
    </div>

<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('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！請從新輸入！');
                $(".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");//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
        
        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];//獲得隨機的一個內容
            show_num[i] = txt.toLowerCase();
            var x = 10 + i * 20;//文字在canvas上的x座標
            var y = 20 + Math.random() * 8;//文字在canvas上的y座標
            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() {//獲得隨機的顏色值
        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 + ")";
    }
</script>

</body>
</html>