Js简单实现二维码的特效

1.首先在前端

<p>验&nbsp;证&nbsp;码：
<input type="text" name="yzmtxt" id="yzm1" onblur="checkyzm()">
<span id="yzm2" onclick="loadyzm()"  style="background:url('images/12.jpg')"> </span>

2.在JS文件中进行编写

var yzm="";
function loadyzm(){


var s=new String("ABCDEFGHIGKLMNOPQRSTUVWXYZqwertyuioplkjhgfdsazxcvbnm0123456789中文字符串随机数测试验证码");
yzm="";
for(var i=0;i<4;i++){
var k=Math.round(Math.random()*(s.length-1) ) ;
yzm+=s.charAt(k);
}
var x=Math.round(Math.random()*14 )+1;
document.getElementById("yzm2").style.background="url('images/"+x+".jpg')";
document.getElementById("yzm2").innerHTML="<font size='5' color='green'>"+yzm+"</font>";
}


function checkyzm(){
var y=document.getElementById("yzm1").value;


if(y.toLowerCase()==yzm.toLowerCase()){
document.getElementById("yzmmess").innerHTML="<font color='green'>正确</font>";
return true;
}else{
document.getElementById("yzmmess").innerHTML="<font color='red'>错误</font>";
loadyzm();
return false;
}
}