我是Web开发的初学者，并且在HTML5的选择选项功能中应用jquery函数slideToggle（）时遇到问题。以下是我将slideToggle（）函数与以下代码配合使用的代码：
//Script for select element
var x, i, j, selElmnt, a, b, c;
/*look for any elements with the class "custom-select":*/
x = document.getElementsByClassName("custom-select");
for (i = 0; i < x.length; i++) {
selElmnt = x[i].getElementsByTagName("select")[0];
/*for each element, create a new DIV that will act as the selected item:*/
a = document.createElement("DIV");
a.setAttribute("class", "select-selected");
a.setAttribute("ID", "select-selected");
a.innerHTML = selElmnt.options[selElmnt.selectedIndex].innerHTML;
x[i].appendChild(a);
/*for each element, create a new DIV that will contain the option list:*/
b = document.createElement("DIV");
b.setAttribute("class", "select-items select-hide");
b.setAttribute("ID", "selectItems");
for (j = 1; j < selElmnt.length; j++) {
/*for each option in the original select element,
create a new DIV that will act as an option item:*/
c = document.createElement("DIV");
c.innerHTML = selElmnt.options[j].innerHTML;
c.addEventListener("click", function(e) {
/*when an item is clicked, update the original select box,
and the selected item:*/
var y, i, k, s, h;
s = this.parentNode.parentNode.getElementsByTagName("select")[0];
h = this.parentNode.previousSibling;
for (i = 0; i < s.length; i++) {
if (s.options[i].innerHTML == this.innerHTML) {
s.selectedIndex = i;
h.innerHTML = this.innerHTML;
y = this.parentNode.getElementsByClassName("same-as-selected");
for (k = 0; k < y.length; k++) {
y[k].removeAttribute("class");
}
this.setAttribute("class", "same-as-selected");
break;
}
}
h.click();
});
b.appendChild(c);
}
x[i].appendChild(b);
a.addEventListener("click", function(e) {
/*when the select box is clicked, close any other select boxes,
and open/close the current select box:*/
e.stopPropagation();
closeAllSelect(this);
this.nextSibling.classList.toggle("select-hide");
this.classList.toggle("select-arrow-active");
});
}
function closeAllSelect(elmnt) {
/*a function that will close all select boxes in the document,
except the current select box:*/
var x, y, i, arrNo = [];
x = document.getElementsByClassName("select-items");
y = document.getElementsByClassName("select-selected");
for (i = 0; i < y.length; i++) {
if (elmnt == y[i]) {
arrNo.push(i)
} else {
y[i].classList.remove("select-arrow-active");
}
}
for (i = 0; i < x.length; i++) {
if (arrNo.indexOf(i)) {
x[i].classList.add("select-hide");
}
}
}
/*if the user clicks anywhere outside the select box,
then close all select boxes:*/
document.addEventListener("click", closeAllSelect);
//select dropdown slide function
$(document).ready(function(){
$("#select-selected").click(function(){
$("#selectItems").slideToggle("slow");
});
});/*the container must be positioned relative:*/
.custom-select {
position: relative;
font-family: myTrench
}
.custom-select select {
display: none; /*hide original SELECT element:*/
}
/*hide default select in IE8*/
select::-ms-expand {
display: none;
}
/*style the arrow inside the select element:*/
.select-selected:after {
position: absolute;
content: "";
top: 40px;
right: 5px;
width: 0;
height: 0;
border: 10px solid transparent;
border-color: #212121 transparent transparent transparent;
}
/*point the arrow upwards when the select box is open (active):*/
.select-selected.select-arrow-active:after {
border-color: transparent transparent #212121 transparent;
top: 20px;
}
/*style the items (options), including the selected item:*/
.select-items div,.select-selected {
color: #212121;
padding: 30px 16px;
border: 1px solid transparent;
border-color: transparent transparent rgba(0, 0, 0, 0.1) transparent;
cursor: pointer;
user-select: none;
font-size: 20px;
height: 5px
}
.select-selected {
background-color: #06FFFB;
height: 30px;
font-size: 22px;
font-weight: 900;
color: #212121
}
/*style items (options):*/
.select-items {
position: absolute;
background-color: #06FFFB;
top: 100%;
left: 0;
right: 0;
z-index: 99;
}
/*hide the items when the select box is closed:*/
.select-hide {
display: none;
}
.select-items div:hover, .same-as-selected {
background-color: #85FCFF;
}<div style="position: absolute; left: 35%; top: 5%">
<span> Choose Income Tax Rate:</span><br><br>
<div class="custom-select" style="width:400px">
<select id="itrate">
<option value="0">Choose income tax rate as per your requirement...</option>
<option value=".03">3% -Transportation, IT services etc...</option>
<option value=".08">8% -Services|Companies|Filer</option>
<option value=".1">10% -Services|Individuals|Filer</option>
<option value=".07">7% -Contract Services|Companies|Filer</option>
<option value=".075">7.5% -Contract Services|Individuals|Filer</option>
</select>
</div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
问题是，当我第一次单击“选择选项” div时，它会产生非常难看的幻灯片效果。另外，根据此脚本，当用户单击div以外的任何位置时，选择选项菜单应自动隐藏，并且在应用此“ slideToggle（）”函数后不会发生这种情况。
PS：我从w3schools网站复制了样式代码（css + javascript）。我只在其javascript代码中添加了一个ID，并尝试在其上应用slideToggle（）效果。请指导我在哪里出错了？