我不希望下拉默认选择的选项单独显示，但为什么会发生这种情况。
是否有一个选项可以跳过特定下拉列表的 jquery 设置？喜欢使用一些像preventDefault这样的函数吗？
请参考以下网址。
[1]：https://jsfiddle.net/ufLr0wo2/
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
<script src="http://code.jquery.com/mobile/1.5.0-rc1/jquery.mobile-1.5.0-rc1.min.js"></script>
</head>
<body>
<div class="">
<form>
<select>
<option value="0">item 0</option>
<option>item 1</option>
<option>item 2</option>
</select>
</form>
</div>
</body>
</html>
如果您使用“nice-select”库来增强下拉菜单，并且希望防止单独显示默认选定的选项，则可以通过配置库的选项或自定义其行为来实现此目的。
“nice-select”库增强了原生 HTML 选择元素的外观和功能。默认情况下，它会单独显示所选选项，以提供更好的用户体验。
为了防止默认选择的选项单独显示，您可能需要自定义库的 CSS 或 JavaScript。
具体操作方法如下：
这是您的代码，其中包含一个基本示例，说明如何使用“nice-select”并应用 CSS 来隐藏默认选定的选项：
$(document).ready(function() {
$('select').niceSelect();
});.nice-select {
-webkit-tap-highlight-color: transparent;
background-color: #fff;
border-radius: 5px;
border: solid 1px #e8e8e8;
box-sizing: border-box;
clear: both;
cursor: pointer;
display: block;
float: left;
font-family: inherit;
font-size: 14px;
font-weight: normal;
height: 42px;
line-height: 40px;
outline: none;
padding-left: 18px;
padding-right: 30px;
position: relative;
text-align: left !important;
-webkit-transition: all 0.2s ease-in-out;
transition: all 0.2s ease-in-out;
-webkit-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
white-space: nowrap;
width: auto; }
.nice-select:hover {
border-color: #dbdbdb; }
.nice-select:active, .nice-select.open, .nice-select:focus {
border-color: #999; }
.nice-select:after {
border-bottom: 2px solid #999;
border-right: 2px solid #999;
content: '';
display: block;
height: 5px;
margin-top: -4px;
pointer-events: none;
position: absolute;
right: 12px;
top: 50%;
-webkit-transform-origin: 66% 66%;
-ms-transform-origin: 66% 66%;
transform-origin: 66% 66%;
-webkit-transform: rotate(45deg);
-ms-transform: rotate(45deg);
transform: rotate(45deg);
-webkit-transition: all 0.15s ease-in-out;
transition: all 0.15s ease-in-out;
width: 5px; }
.nice-select.open:after {
-webkit-transform: rotate(-135deg);
-ms-transform: rotate(-135deg);
transform: rotate(-135deg); }
.nice-select.open .list {
opacity: 1;
pointer-events: auto;
-webkit-transform: scale(1) translateY(0);
-ms-transform: scale(1) translateY(0);
transform: scale(1) translateY(0); }
.nice-select.disabled {
border-color: #ededed;
color: #999;
pointer-events: none; }
.nice-select.disabled:after {
border-color: #cccccc; }
.nice-select.wide {
width: 100%; }
.nice-select.wide .list {
left: 0 !important;
right: 0 !important; }
.nice-select.right {
float: right; }
.nice-select.right .list {
left: auto;
right: 0; }
.nice-select.small {
font-size: 12px;
height: 36px;
line-height: 34px; }
.nice-select.small:after {
height: 4px;
width: 4px; }
.nice-select.small .option {
line-height: 34px;
min-height: 34px; }
.nice-select .list {
background-color: #fff;
border-radius: 5px;
box-shadow: 0 0 0 1px rgba(68, 68, 68, 0.11);
box-sizing: border-box;
margin-top: 4px;
opacity: 0;
overflow: hidden;
padding: 0;
pointer-events: none;
position: absolute;
top: 100%;
left: 0;
-webkit-transform-origin: 50% 0;
-ms-transform-origin: 50% 0;
transform-origin: 50% 0;
-webkit-transform: scale(0.75) translateY(-21px);
-ms-transform: scale(0.75) translateY(-21px);
transform: scale(0.75) translateY(-21px);
-webkit-transition: all 0.2s cubic-bezier(0.5, 0, 0, 1.25), opacity 0.15s ease-out;
transition: all 0.2s cubic-bezier(0.5, 0, 0, 1.25), opacity 0.15s ease-out;
z-index: 9; }
.nice-select .list:hover .option:not(:hover) {
background-color: transparent !important; }
.nice-select .option {
cursor: pointer;
font-weight: 400;
line-height: 40px;
list-style: none;
min-height: 40px;
outline: none;
padding-left: 18px;
padding-right: 29px;
text-align: left;
-webkit-transition: all 0.2s;
transition: all 0.2s; }
.nice-select .option:hover, .nice-select .option.focus, .nice-select .option.selected.focus {
background-color: #f6f6f6; }
.nice-select .option.selected {
font-weight: bold; }
.nice-select .option.disabled {
background-color: transparent;
color: #999;
cursor: default; }
.no-csspointerevents .nice-select .list {
display: none;
}
.no-csspointerevents .nice-select.open .list {
display: block; }<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/jquery-nice-select/1.1.0/css/nice-select.css">
</head>
<body>
<select>
<option data-display="Select">Nothing</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3" disabled>3</option>
<option value="4">4</option>
</select>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery-nice-select/1.1.0/js/jquery.nice-select.min.js"></script>
</body>
</html>