javascript - 如何正确填充此下拉列表？

Question

我正在尝试使用带有一系列元素(项目)的 jquery 填充下拉菜单，但它不起作用。从界面我看到按钮“下拉”，但如果我点击它，我看不到任何东西，我该如何解决这个问题？当我点击它时，我应该看到我传递给它的项目列表(参见 javascript 循环)

.dropbtn {
  background-color: #3498DB;
  color: white;
  padding: 16px;
  font-size: 16px;
  border: none;
  cursor: pointer;
}


/* Dropdown button on hover & focus */

.dropbtn:hover,
.dropbtn:focus {
  background-color: #2980B9;
}


/* The container <div> - needed to position the dropdown content */

.dropdown {
  position: relative;
  display: inline-block;
}


/* Dropdown Content (Hidden by Default) */

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f1f1f1;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
  z-index: 1;
}


/* Links inside the dropdown */

.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}


/* Change color of dropdown links on hover */

.dropdown-content a:hover {
  background-color: #ddd
}


/* Show the dropdown menu (use JS to add this class to the .dropdown-content container when the user clicks on the dropdown button) */

.show {
  display: block;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="dropdown">
  <button class="dropbtn">Dropdown</button>
  <div id="myDropdown" class="dropdown-content">
  </div>
</div>

Answer 1

问题是您无法显示下拉菜单。有一条评论说“点击时添加 [.show]”——但你也可以用悬停 css 来做到这一点，所以不需要 js。

.dropbtn:hover + .dropdown-content {
    display:block;
}

将其添加到您的(其他工作片段)中会给出:

var result = {
  "status": 0,
  "message": "OK",
  "projects": ["p1", "p2", "p3"]
}
for (var i = 0; i < result.projects.length; i++) {
  $('#myDropdown').append('<a data-id= "' + i + '">' + result.projects[i] + '</a>');
}

.dropbtn:hover + .dropdown-content {
    display:block;
}


.dropbtn {
  background-color: #3498DB;
  color: white;
  padding: 16px;
  font-size: 16px;
  border: none;
  cursor: pointer;
}


/* Dropdown button on hover & focus */

.dropbtn:hover,
.dropbtn:focus {
  background-color: #2980B9;
}


/* The container <div> - needed to position the dropdown content */

.dropdown {
  position: relative;
  display: inline-block;
}


/* Dropdown Content (Hidden by Default) */

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f1f1f1;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
  z-index: 1;
}


/* Links inside the dropdown */

.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}


/* Change color of dropdown links on hover */

.dropdown-content a:hover {
  background-color: #ddd
}


/* Show the dropdown menu (use JS to add this class to the .dropdown-content container when the user clicks on the dropdown button) */

.show {
  display: block;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="dropdown">
  <button class="dropbtn">Dropdown</button>
  <div id="myDropdown" class="dropdown-content">
  </div>
</div>

如果您确实想要点击它，那么您需要添加一个点击处理程序，例如:

$(".dropbtn").click(() => { $(".dropdown-content").toggleClass("show") });

给予:

var result = {
  "status": 0,
  "message": "OK",
  "projects": ["p1", "p2", "p3"]
}
for (var i = 0; i < result.projects.length; i++) {
  $('#myDropdown').append('<a data-id= "' + i + '">' + result.projects[i] + '</a>');
}
$(".dropbtn").click(() => { $(".dropdown-content").toggleClass("show") });

.dropbtn {
  background-color: #3498DB;
  color: white;
  padding: 16px;
  font-size: 16px;
  border: none;
  cursor: pointer;
}


/* Dropdown button on hover & focus */

.dropbtn:hover,
.dropbtn:focus {
  background-color: #2980B9;
}


/* The container <div> - needed to position the dropdown content */

.dropdown {
  position: relative;
  display: inline-block;
}


/* Dropdown Content (Hidden by Default) */

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f1f1f1;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
  z-index: 1;
}


/* Links inside the dropdown */

.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}


/* Change color of dropdown links on hover */

.dropdown-content a:hover {
  background-color: #ddd
}


/* Show the dropdown menu (use JS to add this class to the .dropdown-content container when the user clicks on the dropdown button) */

.show {
  display: block;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="dropdown">
  <button class="dropbtn">Dropdown</button>
  <div id="myDropdown" class="dropdown-content">
  </div>
</div>