js实现随机验证码（带干扰线）
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前言
验证码是一种区分用户是计算机还是人的公共全自动程序。它可以可以防止恶意破解密码、刷票、论坛灌水、某个黑客对某一个特定注册用户用特定程序暴力破解方式进行不断的登陆尝试等，实际上验证码也是现在很多网站通行的方式，下面我们就用js来实现这个操作。
实现效果
实现思路
- 首先我们需要创建一个图形验证码对象，接收
options对象为参数； - 获取到
id初始化方法，通过拿到的id和参数生成验证码； - 通过
randomColor()方法随机颜色并且绘制干扰线，通过randomColor()方法随机颜色并且绘制干扰点； - 验证验证码，通过
split()方法生成字母的字符串数组，通过randomNum()随机数方法生成一个随机数，通过randomNum()随机数方法生成一个随机色。
完整代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>随机验证码（带干扰线）</title>
</head>
<style>
.codeVesselBox
width: 120px;
height: 30px;
margin-bottom: 4px;
</style>
<body>
<div>
<div class="codeVesselBox" id="vCodeImg"></div>
<div class="iptBox">
<input id="id" type="text">
<button onclick="threeFn()">提交</button>
</div>
</div>
</body>
<script>
(function (window, document)
function GVerify(options) //创建一个图形验证码对象，接收options对象为参数
this.options = //默认options参数值
id: "", //容器Id
canvasId: "verifyCanvas", //canvas的ID
width: "100", //默认canvas宽度
height: "30", //默认canvas高度
type: "blend", //图形验证码默认类型blend:数字字母混合类型、number:纯数字、letter:纯字母
code: ""
if (Object.prototype.toString.call(options) == "[object Object]") //判断传入参数类型
for (var i in options) //根据传入的参数，修改默认参数值
this.options[i] = options[i];
else
this.options.id = options;
this.options.numArr = "0,1,2,3,4,5,6,7,8,9".split(",");
this.options.letterArr = getAllLetter();
this._init();
this.refresh();
GVerify.prototype =
//版本号
version: '1.0.0',
//初始化方法
_init: function ()
var con = document.getElementById(this.options.id);
var canvas = document.createElement("canvas");
this.options.width = con.offsetWidth > 0 ? con.offsetWidth : "100";
this.options.height = con.offsetHeight > 0 ? con.offsetHeight : "30";
canvas.id = this.options.canvasId;
canvas.width = this.options.width;
canvas.height = this.options.height;
canvas.style.cursor = "pointer";
canvas.innerHTML = "您的浏览器版本不支持canvas";
con.appendChild(canvas);
var parent = this;
canvas.onclick = function ()
parent.refresh();
,
//生成验证码
refresh: function ()
this.options.code = "";
var canvas = document.getElementById(this.options.canvasId);
if (canvas.getContext)
var ctx = canvas.getContext('2d');
else
return;
ctx.textBaseline = "middle";
ctx.fillStyle = randomColor(100, 240);
ctx.fillRect(0, 0, this.options.width, this.options.height);
if (this.options.type == "blend") //判断验证码类型
var txtArr = this.options.numArr.concat(this.options.letterArr);
else if (this.options.type == "number")
var txtArr = this.options.numArr;
else
var txtArr = this.options.letterArr;
for (var i = 1; i <= 4; i++)
var txt = txtArr[randomNum(0, txtArr.length)];
this.options.code += txt;
ctx.font = randomNum(this.options.height / 1.2, this.options.height) + 'px SimHei'; //随机生成字体大小
ctx.fillStyle = randomColor(1, 160); //随机生成字体颜色
// ctx.shadowOffsetX = randomNum(-3, 3);
// ctx.shadowOffsetY = randomNum(-3, 3);
// ctx.shadowBlur = randomNum(-3, 3);
ctx.shadowColor = "rgba(0, 0, 0, 0.3)";
var x = this.options.width / 5 * i;
var y = this.options.height / 2;
var deg = randomNum(-30, 30);
//设置旋转角度和坐标原点
ctx.translate(x, y);
ctx.rotate(deg * Math.PI / 180);
ctx.fillText(txt, 0, 0);
//恢复旋转角度和坐标原点
ctx.rotate(-deg * Math.PI / 180);
ctx.translate(-x, -y);
//绘制干扰线
for (var i = 0; i < 4; i++)
ctx.strokeStyle = randomColor(40, 180);
ctx.beginPath();
ctx.moveTo(randomNum(0, this.options.width), randomNum(0, this.options.height));
ctx.lineTo(randomNum(0, this.options.width), randomNum(0, this.options.height));
ctx.stroke();
//绘制干扰点
for (var i = 0; i < this.options.width / 6; i++) //this.options.width / 6，除以的值越大，点越少
ctx.fillStyle = randomColor(0, 255);
ctx.beginPath();
ctx.arc(randomNum(0, this.options.width), randomNum(0, this.options.height), 1, 0, 2 * Math.PI);
ctx.fill();
,
//验证验证码
validate: function (code)
var code = code.toLowerCase();
// toLowerCase() 方法用于把字符串转换为小写。
var v_code = this.options.code.toLowerCase();
console.log(code);
if (code == v_code)
return true;
else
this.refresh();
return false;
//生成字母数组
function getAllLetter()
var letterStr = "a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
return letterStr.split(",");
//生成一个随机数
function randomNum(min, max)
return Math.floor(Math.random() * (max - min) + min);
//生成一个随机色
function randomColor(min, max)
var r = randomNum(min, max);
var g = randomNum(min, max);
var b = randomNum(min, max);
return "rgb(" + r + "," + g + "," + b + ")";
window.GVerify = GVerify;
)(window, document);
// 调用GVerifty
var verifyCode = new GVerify("vCodeImg");
console.log(verifyCode.options.code);
function threeFn()
var a = document.getElementById('id').value;
if (a != verifyCode.options.code)
alert("验证码错误")
console.log(a, "验证码的值...");
else
alert("验证码正确")
console.log(a, "验证码的值...");
</script>
</html>
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