如何在复选框中显示所选项目的数量？

Question

如何显示 selected 项目的数量？

我尝试了不同的方法来计算复选框的数量，但是当我点击“select 全部”时它没有计算项目。

我想显示这些项目的数量。

这是我正在使用的代码。

这是代码的来源。 https://www.freakyjolly.com/jquery-checkbox-list-select-unselect-all-with-indeterminate-master-check-example-tutorial/

HTML

<div class="container">
  <div class="card">
    <div class="card-header">
      <ul class="list-group list-group-flush">
        <li class="list-group-item">
          <input
            class="form-check-input"
            type="checkbox"
            value="selectAll"
            id="masterCheck"
          />
          <label class="form-check-label" for="masterCheck">
            Select / Unselect All
          </label>
        </li>
      </ul>
    </div>
    <div class="card-body">
      <ul class="list-group list-group-flush" id="list-wrapper">
        <li class="list-group-item">
          <input
            class="form-check-input"
            type="checkbox"
            value="item1"
            id="item1"
          />
          <label class="form-check-label" for="item1">
            Item 1
          </label>
        </li>
        <li class="list-group-item">
          <input
            class="form-check-input"
            type="checkbox"
            value="item2"
            id="item2"
          />
          <label class="form-check-label" for="item2">
            Item 2
          </label>
        </li>
        <li class="list-group-item">
          <input
            class="form-check-input"
            type="checkbox"
            value="item3"
            id="item3"
          />
          <label class="form-check-label" for="item3">
            Item 3
          </label>
        </li>
        <li class="list-group-item">
          <input
            class="form-check-input"
            type="checkbox"
            value="item4"
            id="item4"
          />
          <label class="form-check-label" for="item4">
            Item 4
          </label>
        </li>
        <li class="list-group-item">
          <input
            class="form-check-input"
            type="checkbox"
            value="item5"
            id="item5"
          />
          <label class="form-check-label" for="item5">
            Item 5
          </label>
        </li>
        <li class="list-group-item" id="selected-values"></li>
      </ul>
    </div>
  </div>
</div>

jQuery

$(function() {
    // ID selector on Master Checkbox
    var masterCheck = $("#masterCheck");
    // ID selector on Items Container
    var listCheckItems = $("#list-wrapper :checkbox");

    // Click Event on Master Check
    masterCheck.on("click", function() {
      var isMasterChecked = $(this).is(":checked");
      listCheckItems.prop("checked", isMasterChecked);
      getSelectedItems();
    });

    // Change Event on each item checkbox
    listCheckItems.on("change", function() {
      // Total Checkboxes in list
      var totalItems = listCheckItems.length;
      // Total Checked Checkboxes in list
      var checkedItems = listCheckItems.filter(":checked").length;

      //If all are checked
      if (totalItems == checkedItems) {
        masterCheck.prop("indeterminate", false);
        masterCheck.prop("checked", true);
      }
      // Not all but only some are checked
      else if (checkedItems > 0 && checkedItems < totalItems) {
        masterCheck.prop("indeterminate", true);
      }
      //If none is checked
      else {
        masterCheck.prop("indeterminate", false);
        masterCheck.prop("checked", false);
      }
      getSelectedItems();
    });

    function getSelectedItems() {
      var getCheckedValues = [];
      getCheckedValues = [];
      listCheckItems.filter(":checked").each(function() {
        getCheckedValues.push($(this).val());
      });
      $("#selected-values").html(JSON.stringify(getCheckedValues));
    }
  });

Answer 1

您可以使用简单的 getCheckedValues.length，例如：

$(function() {
    // ID selector on Master Checkbox
    var masterCheck = $("#masterCheck");
    // ID selector on Items Container
    var listCheckItems = $("#list-wrapper :checkbox");

    // Click Event on Master Check
    masterCheck.on("click", function() {
      var isMasterChecked = $(this).is(":checked");
      listCheckItems.prop("checked", isMasterChecked);
      getSelectedItems();
    });

    // Change Event on each item checkbox
    listCheckItems.on("change", function() {
      // Total Checkboxes in list
      var totalItems = listCheckItems.length;
      // Total Checked Checkboxes in list
      var checkedItems = listCheckItems.filter(":checked").length;

      //If all are checked
      if (totalItems == checkedItems) {
        masterCheck.prop("indeterminate", false);
        masterCheck.prop("checked", true);
      }
      // Not all but only some are checked
      else if (checkedItems > 0 && checkedItems < totalItems) {
        masterCheck.prop("indeterminate", true);
      }
      //If none is checked
      else {
        masterCheck.prop("indeterminate", false);
        masterCheck.prop("checked", false);
      }
      getSelectedItems();
    });

    function getSelectedItems() {
      var getCheckedValues = [];
      getCheckedValues = [];
      listCheckItems.filter(":checked").each(function() {
        getCheckedValues.push($(this).val());
      });
      $("#selected-values").html(JSON.stringify(getCheckedValues));
      $("#selected-number").html('<p>Number of element selected: '+ getCheckedValues.length + '</p>');
    }
  });

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="container">
  <div class="card">
    <div class="card-header">
      <ul class="list-group list-group-flush">
        <li class="list-group-item">
          <input
            class="form-check-input"
            type="checkbox"
            value="selectAll"
            id="masterCheck"
          />
          <label class="form-check-label" for="masterCheck">
            Select / Unselect All
          </label>
        </li>
      </ul>
    </div>
    <div class="card-body">
      <ul class="list-group list-group-flush" id="list-wrapper">
        <li class="list-group-item">
          <input
            class="form-check-input"
            type="checkbox"
            value="item1"
            id="item1"
          />
          <label class="form-check-label" for="item1">
            Item 1
          </label>
        </li>
        <li class="list-group-item">
          <input
            class="form-check-input"
            type="checkbox"
            value="item2"
            id="item2"
          />
          <label class="form-check-label" for="item2">
            Item 2
          </label>
        </li>
        <li class="list-group-item">
          <input
            class="form-check-input"
            type="checkbox"
            value="item3"
            id="item3"
          />
          <label class="form-check-label" for="item3">
            Item 3
          </label>
        </li>
        <li class="list-group-item">
          <input
            class="form-check-input"
            type="checkbox"
            value="item4"
            id="item4"
          />
          <label class="form-check-label" for="item4">
            Item 4
          </label>
        </li>
        <li class="list-group-item">
          <input
            class="form-check-input"
            type="checkbox"
            value="item5"
            id="item5"
          />
          <label class="form-check-label" for="item5">
            Item 5
          </label>
        </li>
        <li class="list-group-item" id="selected-values">[]</li>
        <li class="list-group-item" id="selected-number">Number of element selected: 0</li>
      </ul>
    </div>
  </div>
</div>

参考：

Array.prototype.length

如何在复选框中显示所选项目的数量？

How do I display number of selected items in checkbox?

javascript

tags

testing

checkbox

jquery