document.querySelector('span').innerText = getCode()
        document.getElementById('linkbt').addEventListener('click',function(){
            getCode()
        })
        document.querySelector('button').addEventListener('click',function(){
            
            if(document.querySelector('input').value == document.querySelector('span').innerText){
                alert('验证码正确')
            }else{
                alert('验证码失败')
                document.querySelector('input').value = ''
                getCode()
            }
        })
        function getCode(){
            var str = ''
            var arr = [1,2,3,5,6,4,7,8,9,0,'a','b','c','d','e','f']
            for(var i = 0 ; i<6;i++){
                var num = Math.round(Math.random()*(15-0)+0)
                str += arr[num]
            }
            return str
        }