javascript - mobiscroll关于treelist的使用问题

Question

<input type="text" placeholder="请输入桌号" class="input-text" readonly="readonly"  id="listUnordered-show"/>

<ul id="listUnordered-demo" style="display:none">
                <li data-val="Eastern pision">East
                    <ul>
                        <li data-val="Marketing">Marketing
                            <ul>
                                <li data-val="Eden E">Eden E</li>
                                <li data-val="Milda J">Milda J</li>
                                <li data-val="Porfirio R">Porfirio R</li>
                            </ul>
                        </li>
                        <li data-val="Research & Development">R&D
                            <ul>
                                <li data-val="Frances P">Frances P</li>
                                <li data-val="Frank D">Frank D</li>
                            </ul>
                        </li>
                        
            </ul>

<script>
            $('#listUnordered-show').click(function() {
                $('#listUnordered-demo').mobiscroll('show');
                return false;
            });
            $('#listUnordered-demo').mobiscroll().treelist({
                theme: 'ios',
                lang: 'zh',
                display: 'bottom',
                width: [90, 160, 170],
                placeholder: 'Please Select ...',
                labels: ['Region', 'Supervisor', 'Tech']
            });
        </script>

为何会多余出来一个input