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js+canvas实现验证码功能

2019-01-08 JavaScript 前端之家

前端之家收集整理的这篇文章主要介绍了js+canvas实现验证码功能，前端之家小编觉得挺不错的，现在分享给大家，也给大家做个参考。

@H_502_0@刚刚开始接触canvas，写个验证码小功能练练手，实现效果图如下：

@H_502_0@主要代码如下:

@H_502_0@html

<Meta charset="UTF-8"> <Meta name="viewport" content="width=device-width,initial-scale=1.0"> <Meta http-equiv="X-UA-Compatible" content="ie=edge"> Document

Box">

@H_502_0@css

.wrapper {
width: 345px;
border: 1px solid #ccc;
border-radius: 10px;
padding: 20px 10px;
margin: 30px 30px;
}

.inputBox {
width: 345px;
margin: 0 auto 10px;
position: relative;
}

.inputBox .inputCaptcha {
display: inline-block;
height: 50px;
width: 86%;
text-indent: 1em;
border: 1px solid #ddd;
border-radius: 5px;
}

.inputBox .captchaIcon {
display: none;
position: absolute;
top: 50%;
right: 0px;
margin-top: -16px;
width: 32px;
height: 32px;
background-size: 100% 100%;
}

.errorText {
width: 345px;
margin: 0 auto;
font-size: 12px;
color: red;
display: none;
}

.canvasBox {
width: 345px;
margin: 10px auto;
position: relative;
}

canvasCaptcha {

border-radius: 10px;
}

.canvasBox .refresh {
width: 34px;
height: 34px;
position: absolute;
right: 0px;
top: 50%;
margin-top: -17px;
border: 0;
border-radius: 6px;
background-image: url('./images/update.png');
background-size: cover;
}

.captchaSubmit {
padding: 10px 20px;
background-color: #62b900;
border: 0;
font-size: 20px;
border-radius: 5px;
color: #fff;
}

@H_502_0@js

90&&i<97){ continue; } arr.push(String.fromCharCode(i)); } //每个验证码可能出现的字母或数字(区分大小写) var len = arr.length; //验证码的长度 var canvasStr,value; //验证码值 function createCanvas(){ canvasStr = ''; value = ''; for(var i =0 ;i < 6;i++){ var a = arr[Math.floor(Math.random()*len)]; canvasStr += a+' '; value += a; } //canvas var oCanvas = document.getElementById('canvasCaptcha'); var ctx = oCanvas.getContext('2d'); var w = oCanvas.width; var h = oCanvas.height; var oImg = new Image(); oImg.src = './images/bg.jpg'; oImg.onload = function(){ var pattern = ctx.createPattern(oImg,'repeat'); ctx.fillStyle = pattern; ctx.fillRect(0,w,h); ctx.fillStyle = '#ccc'; ctx.textAlign = 'center'; ctx.font = '46px Roboto Slab'; ctx.setTransform(1,-0.12,0.2,12); ctx.fillText(canvasStr,w/2,60); } }

createCanvas();

//验证输入的验证码与图中验证码时候相等
function captcha(e){
if(e == value){
return true;
}
else{
return false;
}
}

//点击提交按钮时的结果
function showResult(){
var inputValue = $('.inputCaptcha').val();

if(inputValue == '' ||inputValue == null || inputValue == 'undefined'){
$('.errorText').css({display:'inline-block'}).html('验证码不能为空,请重新输入!');
$('.captchaIcon').css({display:'inline-block',backgroundImage:"url('./images/false.png')"});
}else{
var flag = captcha(inputValue);
if(!flag){
$('.errorText').css({display:'inline-block'}).html('验证码错误,请重新输入!');
$('.captchaIcon').css({display:'inline-block',backgroundImage:"url('./images/false.png')"});
}else{
$('.captchaIcon').css({display:'inline-block',backgroundImage:"url('./images/true.png')"});
}
}
}
$('.captchaSubmit').click(showResult);//提交
$('.refresh').click(createCanvas);//刷新
//点击input框
$('.inputCaptcha').focus(function(){
$('.errorText').add($('.captchaIcon')).fadeOut(100);
})