Home > Article > Web Front-end > Pure JS code to implement image verification code function (compatible with IE6-8)
Pure JS code to implement image verification code function (compatible with IE6-8)
- 零下一度Original
- 2017-04-19 18:02:421997browse
This article mainly introduces the pure JS to implement the image verification code function and is compatible with IE6-8 browsers. Friends who need it can refer to it
I want to build a picture verification code function recently, but I don’t want to write it myself code behind. So I planned to build a pure front-end verification code function, so I searched online and found a plug-in called gVerify.js, which is simple, easy to use, and perfectly implemented. However, I later received a message saying that it would be compatible with IE8, which made me drunk just thinking about it. IE is terrible, but it's okay. I don't think about looking for plug-ins. I plan to do it myself, and use it to learn and strengthen my knowledge. See below how I did it. It took a while, but it was worth it.
How to use
It is very simple to use. Define a p-verification code input box, introduce the downloaded js plug-in, and create a GVerify object. The parameters can be customized or the ID of p can be passed in. This generates a verification code, the effect is shown in Figure 1-1 below.
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>图形验证码</title>
</head>
<body>
<p id="v_container" style="width: 200px;height: 50px;"></p>
<input type="text" id="code_input" value="" placeholder="请输入验证码"/><button id="my_button">验证</button>
</body>
<script src="js/gVerify.js"></script>
<script>
var verifyCode = new GVerify("v_container");
document.getElementById("my_button").onclick = function(){
var res = verifyCode.validate(document.getElementById("code_input").value);
if(res){
alert("验证正确");
}else{
alert("验证码错误");
}
}
</script>
</html>
Figure 1-1
The effect is pretty good, you’re done. It was done in minutes, and there were no problems when clicking on various browsers. But once I get to IE, it's GG. IE9 is still useful, but IE8 is useless. I can only see how it is implemented. So I opened the source code and found that it was implemented by canvas, which is not supported by IE8 and below. This was embarrassing. Then I went to see the relevant introduction to the canvas element, and found that I was really tricked. "We can even use the 5ba626b379994d53f7acf72a64f9b697 tag in IE and build compatible canvases with open source JavaScript code (sponsored by Google) based on IE's VML support. See: http://excanvas.sourceforge. net/." When I saw this sentence, I felt that I was on to something, so I immediately downloaded an excanvas.js and loaded it on the page, thinking that it would be enough to add a js. It turned out that it worked really well, and I was about to show off my When I did the results, I found that it was IE11, something was wrong! So I adjusted to IE8 and found that it still didn't work. It was not as simple as I thought. So I looked through the plug-in source code and found no problems and no errors were reported. So I could only search to see what the problem was.
Modification
I checked the information and found that the createelement() method plug-in canvas is not supported below IE8. You can only add it first Write the canvas element on the page. So I modified the page and modified the code to create canvas to obtain. And added some comments to the source code. The usage method has changed as follows:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>图形验证码</title>
</head>
<body>
<p id="v_container" style="width: 100px;height: 40px;position: relative;top: -61px;left: 230px;">
<canvas id="verifyCanvas" width="100" he.ight="40" style="cursor: pointer;"></canvas>
</p>
<input type="text" id="code_input" value="" placeholder="请输入验证码"/><button id="my_button">验证</button>
</body>
<script src="js/gVerify.js"></script>
<script>
var verifyCode = new GVerify("v_container");
document.getElementById("my_button").onclick = function(){
var res = verifyCode.validate(document.getElementById("code_input").value);
if(res){
alert("验证正确");
}else{
alert("验证码错误");
}
}
</script>
</html>The source code has been modified as follows (red is the modified part) and comments:
!(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{//传入单个对象就是id
this.options.id = options;
}
this.options.numArr = "0,1,2,3,4,5,6,7,8,9".split(",");//数字
this.options.letterArr = getAllLetter();//生成字母数组
this._init();//初始化
this.refresh();//生成验证码
}
GVerify.prototype = {
/**版本号**/
version: '1.0.0',
/**初始化方法**/
_init: function() {
var con = document.getElementById(this.options.id);//获得验证码的p
var canvas = document.getElementById(this.options.canvasId);//获得画布 IE不能支持canvas，可以增加excanvas.js插件，但是还是不支持createelement()的形式
this.options.width = con.offsetWidth > 0 ? con.offsetWidth : "100";//如果有宽度就使用自己的，没有就默认100
this.options.height = con.offsetHeight > 0 ? con.offsetHeight : "30";//如果有长度就使用自己的，没有就默认30
// canvas.id = this.options.canvasId;//为兼容IE把这些去掉
// 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;//把this赋值parent
canvas.onclick = function(){//验证码点击切换刷新
parent.refresh();
}
},
/**生成验证码**/
refresh: function() {
this.options.code = "";//定义验证码为""
var canvas = document.getElementById(this.options.canvasId);//获得验证码画布
if(canvas.getContext) {//
var ctx = canvas.getContext('2d');//获得绘画对象
}else{//
return;
}
ctx.textBaseline = "middle";
ctx.fillStyle = randomColor(180, 240);
ctx.fillRect(0, 0, this.options.width, this.options.height);//绘制矩形
/* x:矩形起点横坐标（坐标原点为canvas的左上角，当然确切的来说是原始原点，后面写到变形的时候你就懂了，现在暂时不用关系）
y:矩形起点纵坐标
width:矩形长度
height:矩形高度*/
if(this.options.type == "blend") { //判断验证码类型 blend:数字字母混合类型、number:纯数字、letter:纯字母
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)];//取得一个字符
this.options.code += txt;//连接验证码
ctx.font = randomNum(this.options.height/2, this.options.height) + 'px SimHei'; //随机生成字体大小
ctx.fillStyle = randomColor(50, 160); //填充的样式 随机生成字体颜色
ctx.shadowOffsetX = randomNum(-3, 3);//阴影的横向位移量
ctx.shadowOffsetY = randomNum(-3, 3);//阴影的纵向位移量
ctx.shadowBlur = randomNum(-3, 3);//阴影的模糊范围（值越大越模糊）
ctx.shadowColor = "rgba(0, 0, 0, 0.3)";//阴影的颜色
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
*
* 平移context.translate(x,y)
* x:坐标原点向x轴方向平移x
* y:坐标原点向y轴方向平移y
*
* **/
ctx.translate(x, y);
ctx.rotate(deg * Math.PI / 180);//旋转context.rotate(angle)
ctx.fillText(txt, 0, 0);//context.fillText(text,x,y)
/**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);//随机颜色
ctx.beginPath();//路径 context.beginPath()
ctx.moveTo(randomNum(0, this.options.width), randomNum(0, this.options.height));//绘制线段 context.moveTo(x,y) context.lineTo(x,y)
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/4; i++) {
ctx.fillStyle = randomColor(0, 255);
ctx.beginPath();
ctx.arc(randomNum(0, this.options.width), randomNum(0, this.options.height), 1, 0, 2 * Math.PI);// 圆弧context.arc(x, y, radius, starAngle,endAngle, anticlockwise)
ctx.fill();
}
},
/**验证验证码**/
validate: function(code){
var code = code.toLowerCase();
var v_code = this.options.code.toLowerCase();
//console.log(v_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;//设置为window对象
})(window, document);Summary
1. To support IE’s canvas, wxcanvas.js must be introduced and the source code must be modified to obtain the canvas element.
2. Add p and canvas elements to the html.
Show me my verification code again, haha
The above is the detailed content of Pure JS code to implement image verification code function (compatible with IE6-8). For more information, please follow other related articles on the PHP Chinese website!