html

<div class="item-input code-box">
       <input type="text" class="username form-control" id="phone" placeholder="手機號" name="phone" />
       <button type="button" id="get_code">傳送驗證碼</button>
</div>

js

        //獲取驗證碼
        var wait = 60;

        function time(o) {
            if (wait == 0) {
                o.removeAttribute("disabled");
                o.innerHTML = "獲取驗證碼";
                wait = 60;
            } else {
                o.setAttribute("disabled", true);
                o.innerHTML = wait + "秒後重新獲取";
                wait--;
                setTimeout(function () {
                    time(o)
                }, 1000)
            }
        }
        $("#get_code").on("click", function () {
            var phone = $("input[name=phone]").val();
            var _this = document.getElementById("get_code");
            if (!phone) {
                alert('請輸入手機號碼')
                return false;
            } else if (!(/^1[34578]\d{9}$/.test(phone))) {
                alert('請輸入正確的手機號碼')
                return false;
            }
            $.ajax({
                type: "GET",
                url: "url",//請求驗證碼服務端地址
                success: function (data) {
                    if (data.success) {
                        time(_this); //倒計時
                    } else {
                        alert(data.msg)
                    }
                }
            })
        });