使用 HTML、CSS 和 JavaScript 实现可搜索下拉列表并显示选中项

<div class="dropdown">
  <button onclick="myFunction()" class="dropbtn">Dropdown</button>
  <div id="myDropdown" class="dropdown-content">
    <input type="text" placeholder="Search..." id="myInput" onkeyup="filterFunction()">
  </div>
</div>

#myInput {
  box-sizing: border-box;
  background-image: url('searchicon.png'); /* 可选：添加搜索图标 */
  background-position: 14px 12px;
  background-repeat: no-repeat;
  font-size: 16px;
  padding: 14px 20px 12px 45px;
  border: none;
  border-bottom: 1px solid #ddd;
}

#myInput:focus {
  outline: 3px solid #ddd;
}

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

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f6f6f6;
  min-width: 230px;
  border: 1px solid #ddd;
  z-index: 1;
}

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

.dropdown-content a:hover {
  background-color: #f1f1f1;
}

.show {
  display: block;
}

.dropdown-content > .dropdown-option{
  cursor: pointer;
}

.dropdown-content > .selectedOption{
  background-color: darkgray !important;
}

*   从 JSON 数据动态生成下拉选项。
*   实现搜索过滤功能。
*   显示选中的选项。

function myFunction() {
  var country = [
      {
        "ID": "001",
        "Country_Name": "India"
      },
      {
        "ID": "002",
        "Country_Name": "Australia"
      },
      {
        "ID": "003",
        "Country_Name": "Austria"
      },
      {
        "ID": "004",
        "Country_Name": "China"
      },
      {
        "ID": "005",
        "Country_Name": "Bangladesh"
      }
  ];

  document.getElementById("myDropdown").classList.toggle("show");
  var ele = document.getElementById("myDropdown");

  //for each country in the country array
  for (var i = 0; i < country.length; i++) {
    //creates an anchor element
    const countryOption = document.createElement("a");
    //holding the country ID in its value attribute
    countryOption.setAttribute('value', country[i]['ID']);
    //and the country Name as its innerText
    countryOption.innerText = country[i]['Country_Name'];
    //adds the class dropdown-option to the option element
    countryOption.classList.add('dropdown-option');

    //binds the countryOnClick function defined below as its click event handler
    countryOption.addEventListener('click', countryOnClick);

    //appends the new anchor to the dropdown element
    ele.appendChild(countryOption);
  }
}

//click event handler for the dropdown options
function countryOnClick(event){

  //fetch country properties from the element triggering the event
  const clickedOption = event.target;
  const countryID = clickedOption.getAttribute('value');
  const countryName = clickedOption.innerText;

  //removes the selectedOption class to every option in the dropdown
  clickedOption.closest('div').querySelectorAll('.dropdown-option').forEach((o,i)=>{
    o.classList.remove('selectedOption');
  });
  //adds the selectedOption class to the selected option element
  clickedOption.classList.add('selectedOption');

  //show those data on console
  console.log(`${countryID} - ${countryName}`);

  console.log( getSelectedOption() );
}

function getSelectedOption(){
  return document.querySelector('#myDropdown > .dropdown-option.selectedOption');
}

//gets called when the filter input changes, and it filters the dropdown options list
function filterFunction() {
  var input, filter, ul, li, a, i;
  input = document.getElementById("myInput");
  filter = input.value.toUpperCase();
  div = document.getElementById("myDropdown");
  a = div.getElementsByTagName("a");
  for (i = 0; i < a.length; i++) {
    txtValue = a[i].textContent || a[i].innerText;
    if (txtValue.toUpperCase().indexOf(filter) > -1) {
      a[i].style.display = "";
    } else {
      a[i].style.display = "none";
    }
  }
}