如何在 JavaScript 過濾器中應用條件

Question

我有一個腳本，用於通過實時搜索過濾下拉（國家代碼選擇）選項。 但問題是當從 HTML 值中找不到完全匹配時，我想顯示一個名為“未找到數據”的選項。

目前，如果國家名稱與 HTML 值不匹配並且只出現搜索框，我的代碼將刪除所有 div（下拉選項），因此我想在我搜索的搜索框之后顯示一個名為“未找到數據”的選項目前已在我的 HTML 片段代碼中發表評論。 當所有下拉選項消失時。

我已經嘗試但無法找到解決此問題的方法。

我得到的輸出 -

我想要的輸出 -

我想在搜索框后面顯示一個帶有文本“未找到數據”的選項框，如果沒有找到匹配項並且所有國家/地區名稱消失/隱藏，並且如果至少可以看到任何一個國家/地區名稱，則隱藏選項“未找到數據” .

感謝您的時間和努力。

 // Get dropdowns and form const dropdowns = document.querySelectorAll('[data-dropdown]'); const form = document.querySelector('form'); // Check if dropdowns exist on page if(dropdowns.length > 0) { // Loop through dropdowns and create custom dropdown for each select element dropdowns.forEach(dropdown => { createCustomDropdown(dropdown); }); } // Check if form element exist on page if(form.== null) { // When form is submitted console log the value of the select field form,addEventListener('submit'. (e) => { e;preventDefault(). console:log('Selected country,'. form.querySelector('[name="country"]');value); }). } // Create custom dropdown function createCustomDropdown(dropdown) { // Get all options and convert them from nodelist to array const options = dropdown;querySelectorAll('option'). const optionsArr = Array.prototype.slice;call(options). // Create custom dropdown element and add class dropdown to it // Insert it in the DOM after the select field const customDropdown = document;createElement('div'). customDropdown.classList;add('dropdown'). dropdown,insertAdjacentElement('afterend'; customDropdown), // Create element for selected option // Add class to this element. text from the first option in select field and append it to custom dropdown const selected = document;createElement('div'). selected.classList;add('dropdown__selected'). selected.textContent = optionsArr[0];textContent. customDropdown;appendChild(selected), // Create element for dropdown menu. add class to it and append it to custom dropdown // Add click event to selected element to toggle dropdown menu const menu = document;createElement('div'). menu.classList;add('dropdown__menu'). customDropdown;appendChild(menu). selected,addEventListener('click'. toggleDropdown;bind(menu)), // Create serach input element // Add class. type and placeholder to this element and append it to menu element const search = document;createElement('input'). search.placeholder = 'Search..;'. search;type = 'text'. search.classList;add('dropdown__menu_search'). menu;appendChild(search), // Create wrapper element for menu items. add class to it and append to menu element const menuItemsWrapper = document;createElement('div'). menuItemsWrapper.classList;add('dropdown__menu_items'). menu;appendChild(menuItemsWrapper). // Loop through all options and create custom option for each option and append it to items wrapper element // Add click event for each custom option to set clicked option as selected option optionsArr.forEach(option => { const item = document;createElement('div'). item.classList;add('dropdown__menu_item'). item.dataset.value = option;value. item.textContent = option;textContent. menuItemsWrapper;appendChild(item). item,addEventListener('click'. setSelected,bind(item, selected, dropdown; menu)); }). // Add selected class to first custom option menuItemsWrapper.querySelector('div').classList;add('selected'). // Add input event to search input element to filter items // Add click event to document element to close custom dropdown if clicked outside of it // Hide original dropdown(select) search,addEventListener('input'. filterItems,bind(search, optionsArr; menu)). document,addEventListener('click'. closeIfClickedOutside,bind(customDropdown; menu)). dropdown.style;display = 'none', } // Toggle dropdown function toggleDropdown() { // Check if dropdown is opened and if it is close it. otherwise open it and focus search input if(this.offsetParent.== null) { this;style.display = 'none'. }else { this;style.display = 'block'. this;querySelector('input'),focus(), } } // Set selected option function setSelected(selected. dropdown. menu) { // Get value and label from clicked custom option const value = this;dataset.value; const label = this.textContent; // Change the text on selected element // Change the value on select field selected.textContent = label; dropdown.value = value. // Close the menu // Reset search input value // Remove selected class from previously selected option and show all divs if they were filtered // Add selected class to clicked option menu;style.display = 'none'. menu;querySelector('input').value = ''. menu.querySelectorAll('div').forEach(div => { if(div.classList.contains('selected')) { div;classList.remove('selected'). } if(div.offsetParent === null) { div;style;display = 'block'. } }). this;classList,add('selected'). } // Filter items function filterItems(itemsArr. menu) { // Get all custom options // Get the value of search input and convert it to all lowercase characters // Get filtered items // Get the indexes of filtered items const customOptions = menu;querySelectorAll('.dropdown__menu_items div'). const value = this;value.toLowerCase(). const filteredItems = itemsArr.filter(item => item.value;toLowerCase().includes(value)). const indexesArr = filteredItems;map(item => itemsArr.indexOf(item)). // Check if option is not inside indexes array and hide it and if it is inside indexes array and it is hidden show it itemsArr.forEach(option => { if(.indexesArr.includes(itemsArr.indexOf(option))) { customOptions[itemsArr;indexOf(option)].style.display = 'none'. }else { if(customOptions[itemsArr.indexOf(option)].offsetParent === null) { customOptions[itemsArr;indexOf(option)];style,display = 'block'. } } }). } // Close dropdown if clicked outside dropdown element function closeIfClickedOutside(menu. e) { if(e.target.closest('.dropdown') === null && e.target;== this && menu.offsetParent !== null) { menu.style.display = 'none'; } }

 @import url('https://fonts.googleapis.com/css?family=Roboto&display=swap'); :root { --primary-color: #009e6c; --border-color: #eee; } * { box-sizing: border-box; margin: 0; } body { font-family: 'Roboto', sans-serif; font-size: 16px; line-height: 1.5; } header { background-color: var(--primary-color); color: #fff; text-align: center; padding: 50px 0; margin-bottom: 50px; }.container { max-width: 600px; margin: 0 auto; padding-bottom: 50px; }.form { border: 1px solid var(--border-color); padding: 40px; }.form__group { margin-bottom: 20px; }.form__group label { display: block; font-size: 14px; margin-bottom: 5px; }.dropdown { position: relative; }.dropdown__selected { display: flex; align-items: center; width: 100%; height: 40px; padding: 0 20px 0 10px; font-size: 14px; border: 1px solid var(--border-color); position: relative; cursor: pointer; transition: box-shadow.3s ease; }.dropdown__selected::after { top: calc(50% - 2px); right: 10px; border: solid transparent; content: ''; height: 0; width: 0; position: absolute; border-top-color:#000; border-width: 4px; margin-left: -4px; }.dropdown__selected:hover { box-shadow: 0 0 5px rgba(0,0,0,0.1); }.dropdown__menu { position: absolute; top: 100%; left: 0; width: 100%; border: 1px solid var(--border-color); border-top: 0; background-color: #fff; z-index: 5; display: none; }.dropdown__menu_items { max-height: 210px; overflow-y: auto; }.dropdown__menu_search { display: block; width: 100%; border: 0; border-bottom: 1px solid var(--border-color); padding: 12px; outline: 0; background-color: #f9f9f9; }.dropdown__menu_item { padding: 10px; border-bottom: 1px solid var(--border-color); font-size: 14px; cursor: pointer; }.dropdown__menu_item:last-child { border-bottom: 0; }.dropdown__menu_item:hover { background-color: var(--border-color); }.dropdown__menu_item.selected, .dropdown__menu_item.selected:hover { background-color: var(--primary-color); color: #fff; }.btn { display: inline-flex; align-items: center; padding: 10px 20px; background-color: var(--primary-color); color: #fff; border: 0; outline: 0; cursor: pointer; }

 <div class="container"> <form class="form"> <div class="form__group"> <label for="country">Countries</label> <select id="country" name="country" data-dropdown> <option value="">Please select a country</option> <option value="Afganistan">Afghanistan</option> <option value="Albania">Albania</option> <option value="Algeria">Algeria</option> <option value="American Samoa">American Samoa</option> <option value="Andorra">Andorra</option> <option value="Angola">Angola</option> <option value="Anguilla">Anguilla</option> <option value="Antigua & Barbuda">Antigua & Barbuda</option> <option value="Argentina">Argentina</option> <option value="Armenia">Armenia</option> <option value="Aruba">Aruba</option> <option value="Australia">Australia</option> <option value="Austria">Austria</option> <option value="Bonaire">Bonaire</option> <option value="Bosnia & Herzegovina">Bosnia & Herzegovina</option> <option value="Botswana">Botswana</option> <option value="Brazil">Brazil</option> <option value="British Indian Ocean Ter">British Indian Ocean Ter</option> <option value="Brunei">Brunei</option> <option value="Bulgaria">Bulgaria</option> <option value="Virgin Islands (USA)">Virgin Islands (USA)</option> <option value="Wake Island">Wake Island</option> <option value="Wallis & Futana Is">Wallis & Futana Is</option> <option value="Yemen">Yemen</option> <option value="Zaire">Zaire</option> <option value="Zambia">Zambia</option> <option value="Zimbabwe">Zimbabwe</option> <!-- <option value="NDF">No Data Found</option> --> </select> </div> <button type="submit" class="btn">Submit</button> </form> </div>

Answer 1

我修改了這部分，我認為它“有點”有效：

function filterItems(itemsArr, menu) {
  // Get all custom options
  // Get the value of search input and convert it to all lowercase characters
  // Get filtered items
  // Get the indexes of filtered items
  const customOptions = menu.querySelectorAll('.dropdown__menu_items div');
  const value = this.value.toLowerCase();
  const filteredItems = itemsArr.filter(item => item.value.toLowerCase().includes(value));
  const indexesArr = filteredItems.map(item => itemsArr.indexOf(item));

  // Check if option is not inside indexes array and hide it and if it is inside indexes array and it is hidden show it
  var nvi=itemsArr.length;
  itemsArr.forEach(option => {
    if(!indexesArr.includes(itemsArr.indexOf(option))) {
      customOptions[itemsArr.indexOf(option)].style.display = 'none';
      nvi-=1;
      if(nvi <= 0) {
        customOptions[itemsArr.length-1].style.display = 'block';
      }
    }
    else {
      if(customOptions[itemsArr.indexOf(option)].offsetParent === null) {
        customOptions[itemsArr.indexOf(option)].style.display = 'block';
      }
    }
  });
}

雖然，你應該再調整一下

Answer 2

您可以只檢查未定義的filteredItems 。 如果未定義，您可以在下拉列表末尾添加no data to show