Javascript 链接功能在自定义选择菜单中被破坏

我正在一个Wordpress网站上处理一个问题。请参见此处第页：

在右边的边栏中，有一个下拉菜单，我正在尝试使用CSS自定义它，而不是使用默认浏览器。我使用的代码隐藏了旧的下拉菜单，并使用下面的javascript创建了一个新的下拉菜单：

<script>
var x, i, j, l, ll, selElmnt, a, b, c;
/*look for any elements with the class "custom-select":*/
x = document.getElementsByClassName("widget_categories");
l = x.length;
for (i = 0; i < l; i++) {
  selElmnt = x[i].getElementsByTagName("select")[0];
  ll = selElmnt.length;
  /*for each element, create a new DIV that will act as the selected item:*/
  a = document.createElement("DIV");
  a.setAttribute("class", "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");
  for (j = 1; j < ll; 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, sl, yl;
        s = this.parentNode.parentNode.getElementsByTagName("select")[0];
        sl = s.length;
        h = this.parentNode.previousSibling;
        for (i = 0; i < sl; i++) {
          if (s.options[i].innerHTML == this.innerHTML) {
            s.selectedIndex = i;
            h.innerHTML = this.innerHTML;
            y = this.parentNode.getElementsByClassName("same-as-selected");
            yl = y.length;
            for (k = 0; k < yl; 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, xl, yl, arrNo = [];
  x = document.getElementsByClassName("select-items");
  y = document.getElementsByClassName("select-selected");
  xl = x.length;
  yl = y.length;
  for (i = 0; i < yl; i++) {
    if (elmnt == y[i]) {
      arrNo.push(i)
    } else {
      y[i].classList.remove("select-arrow-active");
    }
  }
  for (i = 0; i < xl; 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);
</script>

---

选择框执行以下功能：

    <script type="text/javascript">
/* <![CDATA[ */
(function() {
    var dropdown = document.getElementById( "cat" );
    function onCatChange() {
        if ( dropdown.options[ dropdown.selectedIndex ].value > 0 ) {
            dropdown.parentNode.submit();
        }
    }
    dropdown.onchange = onCatChange;
})();
/* ]]&gt; */
</script>

---

下拉链接功能定义在哪里？新脚本仍然没有修复链接功能，除非我将其错误地放置在结束正文标记之前。您必须向url添加以下参数：例如

    <script type="text/javascript">
/* <![CDATA[ */
(function() {
    var dropdown = document.getElementById( "cat" );
    function onCatChange() {
        if ( dropdown.options[ dropdown.selectedIndex ].value > 0 ) {
            dropdown.parentNode.submit();
        }
    }
    dropdown.onchange = onCatChange;
})();
/* ]]&gt; */
</script>

<form action="http://v2new.brandgineeringbydesign.com" method="get">
</form>

var cat = 190; 
location.href = 'http://v2new.brandgineeringbydesign.com?cat=' + cat;