js实现button点击之后60秒后才可以再次点击

var wait = 60;
    document.getElementById("btn").onclick = function() {
        time(this);
    }
    function time(o) {
        if (wait == 0) {
            o.removeAttribute("disabled");
            o.innerHTML = "免费获取验证码";
            wait = 60;
        } else {
            o.setAttribute("disabled", true);
            o.innerHTML = wait + "秒后可以重新发送";
            wait--;
            setTimeout(function() {
                time(o)
            }, 1000)
        }
    }