javascript - 如何在下拉列表中创建复选框？

Question

我想创建一个多选下拉列表。实际上，我必须使用下拉菜单选择多个选项。当我简单地这样做时，如下所示：

<select>
 <option><input type="checkbox"></option>
</select>

然后复选框显示在下拉字段的前面。但是我想为每个选项而不是整体创建它，以便我可以选择多个选项。有没有办法做到这一点？

Answer 1

这是一个简单的下拉清单：

var checkList = document.getElementById('list1');
checkList.getElementsByClassName('anchor')[0].onclick = function(evt) {
  if (checkList.classList.contains('visible'))
    checkList.classList.remove('visible');
  else
    checkList.classList.add('visible');
}

.dropdown-check-list {
  display: inline-block;
}

.dropdown-check-list .anchor {
  position: relative;
  cursor: pointer;
  display: inline-block;
  padding: 5px 50px 5px 10px;
  border: 1px solid #ccc;
}

.dropdown-check-list .anchor:after {
  position: absolute;
  content: "";
  border-left: 2px solid black;
  border-top: 2px solid black;
  padding: 5px;
  right: 10px;
  top: 20%;
  -moz-transform: rotate(-135deg);
  -ms-transform: rotate(-135deg);
  -o-transform: rotate(-135deg);
  -webkit-transform: rotate(-135deg);
  transform: rotate(-135deg);
}

.dropdown-check-list .anchor:active:after {
  right: 8px;
  top: 21%;
}

.dropdown-check-list ul.items {
  padding: 2px;
  display: none;
  margin: 0;
  border: 1px solid #ccc;
  border-top: none;
}

.dropdown-check-list ul.items li {
  list-style: none;
}

.dropdown-check-list.visible .anchor {
  color: #0094ff;
}

.dropdown-check-list.visible .items {
  display: block;
}

<div id="list1" class="dropdown-check-list" tabindex="100">
  <span class="anchor">Select Fruits</span>
  <ul class="items">
    <li><input type="checkbox" />Apple </li>
    <li><input type="checkbox" />Orange</li>
    <li><input type="checkbox" />Grapes </li>
    <li><input type="checkbox" />Berry </li>
    <li><input type="checkbox" />Mango </li>
    <li><input type="checkbox" />Banana </li>
    <li><input type="checkbox" />Tomato</li>
  </ul>
</div>

Answer 2

这不能仅在 HTML 中完成（将表单元素放入option元素中）。

或者您可以只使用标准select multiple字段。

<select multiple>
  <option value="a">a</option>
  <option value="b">b</option>
  <option value="c">c</option>
</select>

Answer 3

var expanded = false;

function showCheckboxes() {
  var checkboxes = document.getElementById("checkboxes");
  if (!expanded) {
    checkboxes.style.display = "block";
    expanded = true;
  } else {
    checkboxes.style.display = "none";
    expanded = false;
  }
}

.multiselect {
  width: 200px;
}

.selectBox {
  position: relative;
}

.selectBox select {
  width: 100%;
  font-weight: bold;
}

.overSelect {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
}

#checkboxes {
  display: none;
  border: 1px #dadada solid;
}

#checkboxes label {
  display: block;
}

#checkboxes label:hover {
  background-color: #1e90ff;
}

<form>
  <div class="multiselect">
    <div class="selectBox" onclick="showCheckboxes()">
      <select>
        <option>Select an option</option>
      </select>
      <div class="overSelect"></div>
    </div>
    <div id="checkboxes">
      <label for="one">
        <input type="checkbox" id="one" />First checkbox</label>
      <label for="two">
        <input type="checkbox" id="two" />Second checkbox</label>
      <label for="three">
        <input type="checkbox" id="three" />Third checkbox</label>
    </div>
  </div>
</form>

Answer 4

您始终可以使用 multiple 或 multiple = "true" 选项与 select 标签，但有一个 jquery 插件使它更漂亮。它被称为选择，可以在这里找到。

这个小提琴示例可能会帮助您入门

谢谢你。

Answer 5

我不得不提前说，我对Naveen的回答非常有启发，所以我根据这个答案创建了自己的解决方案。

以下 3 个函数是我们多选的基础：

• 初始化功能 - 检测用户何时点击离开以关闭下拉菜单
• 检测用户何时单击下拉菜单以展开它的功能
• 检测复选框单击事件以更新标签的函数

一些改进包括：

• 设计如bootstrap 5
• 点击离开时折叠
• 使用值列表更新标签
• 使用滚动条添加 Y 轴溢出

我也尝试坚持使用原生 JS（没有 jQuery）并尽可能多地使用原生Bootstrap 5样式

这是视频：

我无意制作适合每个人需求的即用型解决方案，因此请根据您的喜好进行调整。我个人期待添加搜索功能。

小提琴：

window.onload = (event) => {
  initMultiselect();
};

function initMultiselect() {
  checkboxStatusChange();

  document.addEventListener("click", function(evt) {
    var flyoutElement = document.getElementById('myMultiselect'),
      targetElement = evt.target; // clicked element

    do {
      if (targetElement == flyoutElement) {
        // This is a click inside. Do nothing, just return.
        //console.log('click inside');
        return;
      }

      // Go up the DOM
      targetElement = targetElement.parentNode;
    } while (targetElement);

    // This is a click outside.
    toggleCheckboxArea(true);
    //console.log('click outside');
  });
}

function checkboxStatusChange() {
  var multiselect = document.getElementById("mySelectLabel");
  var multiselectOption = multiselect.getElementsByTagName('option')[0];

  var values = [];
  var checkboxes = document.getElementById("mySelectOptions");
  var checkedCheckboxes = checkboxes.querySelectorAll('input[type=checkbox]:checked');

  for (const item of checkedCheckboxes) {
    var checkboxValue = item.getAttribute('value');
    values.push(checkboxValue);
  }

  var dropdownValue = "Nothing is selected";
  if (values.length > 0) {
    dropdownValue = values.join(', ');
  }

  multiselectOption.innerText = dropdownValue;
}

function toggleCheckboxArea(onlyHide = false) {
  var checkboxes = document.getElementById("mySelectOptions");
  var displayValue = checkboxes.style.display;

  if (displayValue != "block") {
    if (onlyHide == false) {
      checkboxes.style.display = "block";
    }
  } else {
    checkboxes.style.display = "none";
  }
}

.multiselect {
  width: 100%;
}

.selectBox {
  position: relative;
}

.selectBox select {
  width: 100%;
}

.overSelect {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
}

#mySelectOptions {
  display: none;
  border: 0.5px #7c7c7c solid;
  background-color: #ffffff;
  max-height: 150px;
  overflow-y: scroll;
}

#mySelectOptions label {
  display: block;
  font-weight: normal;
  display: block;
  white-space: nowrap;
  min-height: 1.2em;
  background-color: #ffffff00;
  padding: 0 2.25rem 0 .75rem;
  /* padding: .375rem 2.25rem .375rem .75rem; */
}

#mySelectOptions label:hover {
  background-color: #1e90ff;
}

<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/js/bootstrap.min.js"></script>
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" rel="stylesheet"/>

<div class="container-fluid">


  <div class="form-group col-sm-8">
    <label for="dur">BS original select</label>
    <select id="dur" class="form-select">
      <option value="12" selected>One Year</option>
      <option value="24">Two Year</option>
      <option value="36">Three Year</option>
      <option value="48">Four year</option>
      <option value="60">Five Year</option>
    </select>
  </div>

  <div class="form-group col-sm-8">
    <label for="myMultiselect">BS custom multiselect</label>
    <div id="myMultiselect" class="multiselect">
      <div id="mySelectLabel" class="selectBox" onclick="toggleCheckboxArea()">
        <select class="form-select">
          <option>somevalue</option>
        </select>
        <div class="overSelect"></div>
      </div>
      <div id="mySelectOptions">
        <label for="one"><input type="checkbox" id="one" onchange="checkboxStatusChange()" value="one" /> First checkbox</label>
        <label for="two"><input type="checkbox" id="two" onchange="checkboxStatusChange()" value="two" /> Second checkbox</label>
        <label for="three"><input type="checkbox" id="three" onchange="checkboxStatusChange()" value="three" /> Third checkbox</label>
        <label for="four"><input type="checkbox" id="four" onchange="checkboxStatusChange()" value="four" /> Third checkbox</label>
        <label for="five"><input type="checkbox" id="five" onchange="checkboxStatusChange()" value="five" /> First checkbox</label>
        <label for="six"><input type="checkbox" id="six" onchange="checkboxStatusChange()" value="six" /> Second checkbox</label>
        <label for="seven"><input type="checkbox" id="seven" onchange="checkboxStatusChange()" value="seven" /> Third checkbox</label>
        <label for="eight"><input type="checkbox" id="eight" onchange="checkboxStatusChange()" value="eight" /> First checkbox</label>
        <label for="nine"><input type="checkbox" id="nine" onchange="checkboxStatusChange()" value="nine" /> Second checkbox</label>
        <label for="ten"><input type="checkbox" id="ten" onchange="checkboxStatusChange()" value="ten" /> Third checkbox</label>
      </div>
    </div>
  </div>

</div>

Answer 6

非常简单的带有 Bootstrap 和 JQuery 的代码，没有任何附加的 javascript 代码：

HTML：

<div class="dropdown">
  <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Dropdown button
  </button>
  <form class="dropdown-menu" aria-labelledby="dropdownMenuButton">
    <label class="dropdown-item"><input type="checkbox" name="" value="one">First checkbox</label>
    <label class="dropdown-item"><input type="checkbox" name="" value="two">Second checkbox</label>
    <label class="dropdown-item"><input type="checkbox" name="" value="three">Third checkbox</label>
  </form>
</div>

CSS：

.dropdown-menu label {
  display: block;
}

https://codepen.io/funkycram/pen/joVYBv

Answer 7

带有复选框和 jQuery 的多个下拉菜单。

<div id="list3" class="dropdown-check-list" tabindex="100">
<span class="anchor">Which development(s) are you interested in?</span>
  <ul class="items">
      <li><input id="answers_2529_the-lawns" name="answers[2529][answers][]" type="checkbox" value="The Lawns"/><label for="answers_2529_the-lawns">The Lawns</label></li>
      <li><input id="answers_2529_the-residence" name="answers[2529][answers][]" type="checkbox" value="The Residence"/><label for="answers_2529_the-residence">The Residence</label></li>
  </ul>
</div>

<style>
.dropdown-check-list{
display: inline-block;
width: 100%;
}
.dropdown-check-list:focus{
outline:0;
}
.dropdown-check-list .anchor {
width: 98%;
position: relative;
cursor: pointer;
display: inline-block;
padding-top:5px;
padding-left:5px;
padding-bottom:5px;
border:1px #ccc solid;
}
.dropdown-check-list .anchor:after {
position: absolute;
content: "";
border-left: 2px solid black;
border-top: 2px solid black;
padding: 5px;
right: 10px;
top: 20%;
-moz-transform: rotate(-135deg);
-ms-transform: rotate(-135deg);
-o-transform: rotate(-135deg);
-webkit-transform: rotate(-135deg);
transform: rotate(-135deg);
}
.dropdown-check-list .anchor:active:after {
right: 8px;
top: 21%;
}
.dropdown-check-list ul.items {
padding: 2px;
display: none;
margin: 0;
border: 1px solid #ccc;
border-top: none;
}
.dropdown-check-list ul.items li {
list-style: none;
}
.dropdown-check-list.visible .anchor {
color: #0094ff;
}
.dropdown-check-list.visible .items {
display: block;
}
</style>

<script>
jQuery(function ($) {
        var checkList = $('.dropdown-check-list');
        checkList.on('click', 'span.anchor', function(event){
            var element = $(this).parent();

            if ( element.hasClass('visible') )
            {
                element.removeClass('visible');
            }
            else
            {
                element.addClass('visible');
            }
        });
    });
</script>

Answer 8

只需使用 bootstrap-multiselect，您可以在其中使用多选选项和更多功能填充下拉菜单。

对于文档和教程，您可以访问以下链接

https://www.npmjs.com/package/bootstrap-multiselect

http://davidstutz.de/bootstrap-multiselect/