获取验证码60秒倒计时js

真的是老了，写个js的计时器居然用了20分钟，惭愧

            /*计时器*/
            var wait = 60;
            var e=document.getElementById("btn");
            e.onclick = function() {
                time(this);
            }
           function time(o) {
                if (wait == 0) {
                    o.removeAttribute("disabled");            
                    o.value="获取验证码";
                    wait = 60;
                } else {
                    o.setAttribute("disabled", true);
                    o.value="重新发送(" + wait + ")";
                    wait--;
                    setTimeout(function() {
                    time(o)
                },1000)}
           }