點擊發送短息5秒後跳轉

<script>
    //獲取id，倒數的值，設定定時器的名字，點擊計時器開始（先清除計時器，標籤失效，設定定時器，設定函數，倒數值減少，如果倒數值大於0，內容變；小於，標籤變回，內容變回，計時器停止，倒數值變回）;
    varbtn = document.getElementById("btn");
    varcount = 5;
    vartimer = null;
    btn.onclick= function(){
        clearInterval(timer);
        this.disabled= true;
        varthat =this;
        timer =setInterval(sendText,1000);
        functionsendText(){
            count--;
            if(count >= 0){
                that.innerHTML= ""+ count +"秒後重新發送短信";
            }else{
                that.disabled= false;
                that.innerHTML= "重新發送短信";
                clearInterval(timer);
                count =5;
            }
        }
    }
</script>