(function ($) {

    'use strict';

    var $search = $(".search"),

        $box = $(".search-box"),

        $btn = $(".search-btn"),

        $auto = $(".search-auto");

    // 验证搜索框是否有效    

    $btn.on("click", function () {

        if ($.trim($box.val()) == '') {

            return false;

        }

    })

    $box.on("input", function () {

        var url='https://suggest.taobao.com/sug?code=utf-8&&_ksTS=1564047707915_833&callback=jsonp834&k=1&area=c2c&bucketid=5&q='+$.trim($box.val());

        $.ajax({

            url: url,

            datatype: "jsonp"

        }).done(function (data) {

            console.log(data)

            // var html = "",

            //     maxNum = 5,

            //     num = data['result'].length;

            // if (num == 0) {

            //     $auto.html('').hide();

            //     return;

            // }

            // for (i = 0; i < num; i++) {

            //     if (i >= maxNum) break;

            //     html = "<li>" + data['result'][i][0] + "</li>";

            // }

            // $auto.html(html).show();

        }).fail(function (error) {

            console.log(1);

        })

    })

})(jQuery);

<div class="search">

                <form action="//s.taobao.com/search">

                    <input type="text" placeholder="一元抢" name="q" autocomplete="off" class="search-box">

                    <input type="submit" value="搜索" class="search-btn">

                </form>

                <ul class="search-auto">

                    <!-- <li>1</li>

                    <li>2</li>

                    <li>3</li> -->

                </ul>

            </div>