当搜索栏退格为空时，如何让我的列表不显示？

如何解决当搜索栏退格为空时，如何让我的列表不显示？

每当搜索栏退格为空时，我一直无法让我的项目列表不显示。当您搜索项目并显示它们时，它会起作用。但是，当您退格以清除搜索栏时，它仍会显示整个项目列表！非常感谢您的帮助！

const flavoursBtn = document.getElementById("flavoursBtn");
const flavDropdown = document.getElementById("flavDropdown");
const flavourInput = document.getElementById("flavourInput");
const flavourList = document.getElementsByClassName("flavourList");

flavoursBtn.addEventListener("click",function () {
  flavDropdown.classList.toggle("show");
});

flavourInput.addEventListener("keyup",function (event) {
  let search = event.target.value.toLowerCase();
  let allFlavours = document.getElementsByClassName("flavour");

  for (let i = 0; i < allFlavours.length; i++) {
    const currentFlav = allFlavours[i].textContent.toLowerCase();

    if (currentFlav.includes(search)) {
      allFlavours[i].style.display = "block";
    } else if (currentFlav.value === "") {
      flavourList.style.display = "none";
    } else {
      allFlavours[i].style.display = "none";
    }
  }
});

body {
  background: linear-gradient(to right,#fdfc47,#24fe41);
  font-family: "Cabin",Sans-Serif;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

h1,h2,h3,h4,h5,h6 {
  font-family: "Roboto Condensed",Sans-Serif;
  font-weight: 700;
}

h1 {
  font-size: 3.125rem;
  color: #8738d6;
  text-shadow: 2px 2px 5px #af64ea;
  margin: 0;
}

p {
  font-size: 1.125rem;
  color: white;
  text-shadow: 2px 2px 5px #af64ea;
}

img {
  max-width: 100%;
  height: auto;
}

.container {
  width: 80vw;
  height: 100vh;
  position: relative;
  display: grid;
  grid-gap: 10px;
  grid-template-columns: 1fr 1fr 1fr;
  /*   border: 2px solid red; */
}

.box {
  /*   border: 1px solid red; */
  display: flex;
}

.a {
  grid-column: 1 / 3;
  grid-row: 1 /2;
  flex-direction: column;
  align-items: flex-start;
  justify-content: flex-start;
  padding-top: 25%;
}

.b {
  grid-column: 3;
  grid-row: 1 / 2;
  justify-content: center;
  align-items: center;
}

#flavoursBtn {
  background-color: #8738d6;
  border-radius: 10px;
  color: #24fe41;
  cursor: pointer;
  padding: 10px 20px;
  border: none;
  outline-color: #af64ea;
  box-shadow: 2px 2px 5px #af64ea;
  text-shadow: 1px 1px 1px #fdfc47;
}

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

.dropdown-content {
  display: none;
  position: absolute;
  z-index: 1;
}

.dropdown-content li {
  color: #8738d6;
  padding: 3px 0;
  text-decoration: none;
  display: none;
}

input[type="text"] {
  min-width: 250px;
  padding: 5px 15px;
  margin: 10px 0;
  border-radius: 10px;
  border: 1px solid #af64ea;
  outline-color: #af64ea;
  box-sizing: border-box;
  font-family: "Cabin",Sans-Serif;
  color: #8738d6;
}

::-webkit-input-placeholder {
  /* Edge */
  color: #8738d6;
  font-family: "Cabin",Sans-Serif;
}

:-ms-input-placeholder {
  /* Internet Explorer 10-11 */
  color: #8738d6;
  font-family: "Cabin",Sans-Serif;
}

::placeholder {
  color: #8738d6;
  font-family: "Cabin",Sans-Serif;
}

.show {
  display: block;
}

.hide {
  display: none;
}

<div class="container">
  <div class="box a">
    <div class="dropdown">
      <button id="flavoursBtn">Flavours</button>
      <div id="flavDropdown" class="dropdown-content">
        <input type="text" placeholder="Search..." id="flavourInput">
        <div class="flavours">
          <ul class="flavourList">
            <li class="flavour">Vanilla</li>
            <li class="flavour">Chocolate</li>
            <li class="flavour">Cookies n' Cream</li>
            <li class="flavour">Chocolate Chip Cookie Dough</li>
            <li class="flavour">Peanut Butter Banana</li>
            <li class="flavour">Pistachio</li>
            <li class="flavour">Birthday Cake</li>
            <li class="flavour">Cotton Candy</li>
          </ul>
        </div>
      </div>
    </div>
  </div>
  <div class="box b">
    <img src="https://i.ibb.co/82X9tP7/Scoops.png" alt="Scoops" alt="yummy looking purple ice cream">
  </div>
</div>

解决方法

您的 javascript 在这里：

if (currentFlav.includes(search)) {
  allFlavours[i].style.display = "block";
} else if (currentFlav.value === "") {
  flavourList.style.display = "none";
} else {
  allFlavours[i].style.display = "none";
}

表示如果当前风味为空，则将风味列表显示为无。

问题在于，当您的搜索是“”时，风味列表已完全填充，因此它永远不会被触发。

您还需要使用 flavourList[0] 访问 flavorList，因为 .getElementsByClassName 返回一个元素数组。 （注意复数 .getElements 不是 .getElement）

为了解决这个问题，我添加了一个检查，说明如果搜索是“”，则让 flavorList 显示为无

const flavoursBtn = document.getElementById("flavoursBtn");
const flavDropdown = document.getElementById("flavDropdown");
const flavourInput = document.getElementById("flavourInput");
const flavourList = document.getElementsByClassName("flavourList");

flavoursBtn.addEventListener("click",function () {
  flavDropdown.classList.toggle("show");
});

flavourInput.addEventListener("keyup",function (event) {
  let search = event.target.value.toLowerCase();
  let allFlavours = document.getElementsByClassName("flavour");
  
  if(search === "") {
    flavourList[0].style.display = "none";
    return;
  } else {
    flavourList[0].style.display = "block";
  }

  for (let i = 0; i < allFlavours.length; i++) {
    const currentFlav = allFlavours[i].textContent.toLowerCase();

    if (currentFlav.includes(search)) {
      allFlavours[i].style.display = "block";
    } else {
      allFlavours[i].style.display = "none";
    }
  }
});

body {
  background: linear-gradient(to right,#fdfc47,#24fe41);
  font-family: "Cabin",Sans-Serif;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

h1,h2,h3,h4,h5,h6 {
  font-family: "Roboto Condensed",Sans-Serif;
  font-weight: 700;
}

h1 {
  font-size: 3.125rem;
  color: #8738d6;
  text-shadow: 2px 2px 5px #af64ea;
  margin: 0;
}

p {
  font-size: 1.125rem;
  color: white;
  text-shadow: 2px 2px 5px #af64ea;
}

img {
  max-width: 100%;
  height: auto;
}

.container {
  width: 80vw;
  height: 100vh;
  position: relative;
  display: grid;
  grid-gap: 10px;
  grid-template-columns: 1fr 1fr 1fr;
  /*   border: 2px solid red; */
}

.box {
  /*   border: 1px solid red; */
  display: flex;
}

.a {
  grid-column: 1 / 3;
  grid-row: 1 /2;
  flex-direction: column;
  align-items: flex-start;
  justify-content: flex-start;
  padding-top: 25%;
}

.b {
  grid-column: 3;
  grid-row: 1 / 2;
  justify-content: center;
  align-items: center;
}

#flavoursBtn {
  background-color: #8738d6;
  border-radius: 10px;
  color: #24fe41;
  cursor: pointer;
  padding: 10px 20px;
  border: none;
  outline-color: #af64ea;
  box-shadow: 2px 2px 5px #af64ea;
  text-shadow: 1px 1px 1px #fdfc47;
}

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

.dropdown-content {
  display: none;
  position: absolute;
  z-index: 1;
}

.dropdown-content li {
  color: #8738d6;
  padding: 3px 0;
  text-decoration: none;
  display: none;
}

input[type="text"] {
  min-width: 250px;
  padding: 5px 15px;
  margin: 10px 0;
  border-radius: 10px;
  border: 1px solid #af64ea;
  outline-color: #af64ea;
  box-sizing: border-box;
  font-family: "Cabin",Sans-Serif;
  color: #8738d6;
}

::-webkit-input-placeholder {
  /* Edge */
  color: #8738d6;
  font-family: "Cabin",Sans-Serif;
}

:-ms-input-placeholder {
  /* Internet Explorer 10-11 */
  color: #8738d6;
  font-family: "Cabin",Sans-Serif;
}

::placeholder {
  color: #8738d6;
  font-family: "Cabin",Sans-Serif;
}

.show {
  display: block;
}

.hide {
  display: none;
}

<div class="container">
  <div class="box a">
    <div class="dropdown">
      <button id="flavoursBtn">Flavours</button>
      <div id="flavDropdown" class="dropdown-content">
        <input type="text" placeholder="Search..." id="flavourInput">
        <div class="flavours">
          <ul class="flavourList">
            <li class="flavour">Vanilla</li>
            <li class="flavour">Chocolate</li>
            <li class="flavour">Cookies n' Cream</li>
            <li class="flavour">Chocolate Chip Cookie Dough</li>
            <li class="flavour">Peanut Butter Banana</li>
            <li class="flavour">Pistachio</li>
            <li class="flavour">Birthday Cake</li>
            <li class="flavour">Cotton Candy</li>
          </ul>
        </div>
      </div>
    </div>
  </div>
  <div class="box b">
    <img src="https://i.ibb.co/82X9tP7/Scoops.png" alt="Scoops" alt="yummy looking purple ice cream">
  </div>
</div>