var oText = document.getElementById("text");

var oBtn = document.getElementById("btn");

var val = "";

creatCode()

function creatCode(){

var arr = ['0','1','2','3','4','5','6','7','8','9','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']

val = "";

for (var i=0;i<4;i++) {

var index = Math.floor(Math.random()*62)

val += arr[index];

}

oBtn.value = val;

}

function validate(){

var inputcode = document.getElementById("text").value;

console.log(inputcode.toLowerCase())

if(val.length == 0){

alert("请输入验证码")

}else if(inputcode.toLowerCase() != val.toLowerCase()){

alert("验证码错误")

creatCode();

return false;

}else{

alert("成功！")

return true;

}

}