我試圖在選擇特定選擇選項時顯示“expandrepeat”div。這是我不工作的代碼：<script>window.check=function(elem) {    if (elem.selectedIndex == 1) {        document.getElementById("expandrepeat").style.display = 'block';    } else {        document.getElementById("expandrepeat").style.display = 'none';    }};</script>html:<div class="information-lane"><p class="information-title">{{trans.modal.repeat}}</p><select class="information-input form-control" onChange="check(this);">    <option value="-">No repeat</option>    <option value="-">Daily</option>    <option value="-">Weekly</option>    <option value="-">Monthly</option>    <option value="-">Yearly</option>    <option disabled="disabled">–––––––––––––––––––––––––––––––––––––––––––––</option>    <option value="-">Custom...</option></select></div><div id="expandrepeat" style="display:none;">  <p>Repeat every</p>  <input></div>