js uses setInterval to implement countdown

<button id="code" class="btn btn-default" onclick="getCode();">获取校验码</button>

<script type="text/javascript">  
    var i;  
    function getCode(){  
        $("#code").attr({"disabled":"disabled"});  
        i = self.setInterval("countdown()", 1000);  
    }  
   
    var int = 10  
    function countdown() {  
        document.getElementById("code").innerHTML = int + "秒后重新发送";  
        int--;  
        if(int<0){  
            i=window.clearInterval(i)//结束  
            int = 10; //重新赋值  
            $("#code").removeAttr("disabled").html("重新获取校验码");//将按钮可用  
        }  
    }  
       
</script>