使下拉式選單多層化

Question

我有一個下拉式選單，如下所示：

.dropdown
{
    display: inline-block;
    position: relative;
}
.dropdown button > a
{
    display: block;
    color: #000000;
    text-decoration: none;
}
.dropdown-content
{
    display: none;
    position: absolute;
    width: auto;
    overflow: auto;
    box-shadow: 0px 10px 10px 0px rgba(0,0,0,0.4);
}
.dropdown:hover .dropdown-content
{
    display: block;
}
.dropdown-content a
{
    display: block;
    color: #000000;
    background-color: #e9e9ed;
    padding: 5px;
    text-decoration: none;
}
.dropdown-content a:hover
{
    color: #FFFFFF;
    background-color: #0080bf;
}

<DIV class="dropdown"><BUTTON>Menu</BUTTON><DIV class="dropdown-content">
    <A href="/1.php">Option 1</A>
    <A href="/2.php">Option 2</A>
    <A href="/3.php">Option 3</A>
    <DIV class="dropdown"><BUTTON><A href="/4.php">Option 4</A></BUTTON><DIV class="dropdown-content">
        <A href="/4-1.php">Option 4-1</A>
        <A href="/4-2.php">Option 4-2</A>
        <A href="/4-3.php">Option 4-3</A>
    </DIV></DIV>
</DIV></DIV>

但第二級選單不起作用（按“運行程式碼片段”即可查看）。我需要它顯示在第一級的右側，並且每級的寬度必須是彈性的（根據內容自動增加和減少）。此外，根按鈕的寬度不得綁定到第一級的寬度。理想情況下，任何級別都應該有通用風格，但這並不重要，因為我沒有數十個關卡。有沒有不用重寫所有程式碼的解決方案？

Answer 1

function showNestedDropdown() {
          var firstDropdown = document.getElementById("firstDropdown");
          var nestedDropdownContainer = document.getElementById("nestedDropdownContainer");
      
          if (firstDropdown.value !== "") {
            nestedDropdownContainer.style.display = "block";
          } else {
            nestedDropdownContainer.style.display = "none";
          }
        }

    <select id="firstDropdown" onchange="showNestedDropdown()">
        <option value="">Select an option</option>
        <option value="option1">Option 1</option>
        <option value="option2">Option 2</option>
      </select>
      
      <div id="nestedDropdownContainer" style="display: none;">
        <select id="nestedDropdown">
          <option value="">Select a nested option</option>
          <option value="nested1">Nested Option 1</option>
          <option value="nested2">Nested Option 2</option>
        </select>
      </div>

Answer 2

您可以執行以下操作：

從 .dropdown-content 移除 overflow: auto;，以便溢出的子層級可見。在 .dropdown:hover .dropdown-content 行新增 > 選擇器，以便直接子項目會在懸停時顯示。最後一件事是新增子層級樣式以將其顯示在右上角 .dropdown-content .dropdown-content { left: 100%;頂部：0; }

body {
  background-color: antiquewhite;
}
.dropdown
{
    display: inline-block;
    position: relative;
    width: 100%;
}
.dropdown-content
{
    display: none;
    position: absolute;
    width: auto;
    box-shadow: 0px 10px 10px 0px rgba(0,0,0,0.4);
    white-space: nowrap;
}
.dropdown:hover > .dropdown-content
{
    display: block;
}
.dropdown-content a
{
    display: block;
    color: #000000;
    background-color: #e9e9ed;
    padding: 5px;
    text-decoration: none;
}
.dropdown-content a:hover
{
    color: #FFFFFF;
    background-color: #0080bf;
}

/* To display second level on right*/
.dropdown-content .dropdown-content {
    left: 100%;
    top: 0;
}

<div class="dropdown">
    <div class="menu">Menu</div>
    <div class="dropdown-content">
      <a href="/1.php">Option 1 Longer</a>
      <div class="dropdown">
          <div class="menu">
            <a href="/4.php">Option</a>
          </div>
          <div class="dropdown-content">
            <a href="/4-1.php">Option 4-1</a>
            <a href="/4-2.php">Option 4-2</a>
            <a href="/4-3.php">Option 4-3</a>
        </div>
      </div>
    </div>
</div>