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使用 JavaScript 从列表中删除指定元素

花韻仙語

发布： 2025-10-29 17:32:21

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使用 javascript 从列表中删除指定元素

本文将指导你如何使用 JavaScript 从一个动态生成的列表中删除指定的元素，而不仅仅是最后一个元素。通过修改 `deleteItem` 函数，我们将能够获取点击事件的目标元素，找到它在数组中的索引，并将其从数组和列表中移除。

在网页开发中，经常需要动态地操作列表，例如添加、删除元素。本教程将重点介绍如何使用 JavaScript 实现点击列表项删除该项的功能。核心在于如何准确地获取被点击的元素，并从数据源（数组）中移除对应的项，同时更新页面显示。

HTML 结构调整

首先，我们需要修改 HTML 结构，确保每个列表项都能触发 deleteItem 函数，并传递事件对象 event。关键是将 onclick 事件直接绑定到每个列表项 <li> 元素上，而不是在 <ul> 元素之外。同时，需要将删除按钮（例如 "x"）添加到每个列表项中。

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<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Shopping List</title>

    <!-- Link Google Font -->
    <link href="https://fonts.googleapis.com/css2?family=Nunito&display=swap" rel="stylesheet">
    <!-- External CSS link-->
    <link rel="stylesheet" href="./css/styles.css">
</head>

<body>
    <div class="container">
        <h2>Shopping List</h2>

        <div class="header">
            <input type="text" id="input" placeholder="Item">
            <span onclick="updateList(myArray)" id="addBtn"><button>Add Item</button></span>
        </div>
        <ul id="itemList">
            </ul>
    </div>

    <script src="mainForTask2.js"></script>
</body>

</html>

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JavaScript 代码修改

接下来，修改 JavaScript 代码以实现正确的功能。关键在于 arrayList 函数和 deleteItem 函数。

arrayList 函数: 修改 arrayList 函数，使得每个列表项都包含一个删除按钮，并将 onclick 事件绑定到该按钮上。

let myArray = ["Sugar", "Milk", "Bread", "Apples"];
let list1 = document.querySelector("#itemList");

//This function pushed my array items to create the list
arrayList = (arr) => {
  list1.innerHTML = ''; // Clear the list before re-rendering
  arr.forEach(item => {
    let li = document.createElement('li');
    li.textContent = item;
    let span = document.createElement('span');
    span.innerHTML = '&times;'; // Use &times; for the "x" symbol
    span.onclick = function(event) { // Wrap the function in an anonymous function
      deleteItem(item); // Pass the item itself to deleteItem
      event.stopPropagation(); // Stop the event from bubbling up to the li
    };
    li.appendChild(span);
    list1.appendChild(li);
  });
}

arrayList(myArray)

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deleteItem 函数: 修改 deleteItem 函数，使其接收要删除的项作为参数，并使用 indexOf 方法找到该项在数组中的索引，然后使用 splice 方法将其从数组中删除。

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//This function is meant to delete the specified item chosen by the user from the shopping list and the array
deleteItem = (item) => {
  let index = myArray.indexOf(item);
  if (index > -1) {
    myArray.splice(index, 1);
  }
  arrayList(myArray); // Re-render the list after deleting the item
}

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updateList 函数: 确保 updateList 函数在添加新项后重新渲染列表。

//This function uses the user input from the form to add items to the list
updateList = (arr) => {
  let blue = document.getElementById("input").value;

  if (blue === "") {
    alert("Please enter a value if you wish to add something to your list.")
  } else {
    arr.push(blue);
    arrayList(myArray); // Re-render the list after adding the item
    idSelector()
  }
  document.getElementById("input").value = ""; // Clear the input field
}

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idSelector 函数: 确保 idSelector 函数在重新渲染列表后仍然能够正确地应用样式。

//This function changed the background color of two of the list items to show that they are sold
const idSelector = () => {
  let idElement = document.getElementsByTagName("li")
  if (idElement.length > 0) {
    idElement[0].style.color = "red";
  }
  if (idElement.length > 3) {
    idElement[3].style.color = "red";
  }
}

idSelector()

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完整代码示例

<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Shopping List</title>

    <!-- Link Google Font -->
    <link href="https://fonts.googleapis.com/css2?family=Nunito&display=swap" rel="stylesheet">
    <!-- External CSS link-->
    <link rel="stylesheet" href="./css/styles.css">
</head>

<body>
    <div class="container">
        <h2>Shopping List</h2>

        <div class="header">
            <input type="text" id="input" placeholder="Item">
            <span onclick="updateList(myArray)" id="addBtn"><button>Add Item</button></span>
        </div>
        <ul id="itemList">
            </ul>
    </div>

    <script>
    //This is a javascript program which added the items in my array to an unordered list
    let myArray = ["Sugar", "Milk", "Bread", "Apples"];
    let list1 = document.querySelector("#itemList");

    //This function pushed my array items to create the list
    arrayList = (arr) => {
      list1.innerHTML = ''; // Clear the list before re-rendering
      arr.forEach(item => {
        let li = document.createElement('li');
        li.textContent = item;
        let span = document.createElement('span');
        span.innerHTML = '&times;'; // Use &times; for the "x" symbol
        span.onclick = function(event) { // Wrap the function in an anonymous function
          deleteItem(item); // Pass the item itself to deleteItem
          event.stopPropagation(); // Stop the event from bubbling up to the li
        };
        li.appendChild(span);
        list1.appendChild(li);
      });
    }

    arrayList(myArray)


    //This function changed the background color of two of the list items to show that they are sold
    const idSelector = () => {
      let idElement = document.getElementsByTagName("li")
      if (idElement.length > 0) {
        idElement[0].style.color = "red";
      }
      if (idElement.length > 3) {
        idElement[3].style.color = "red";
      }
    }

    idSelector()

    //This function uses the user input from the form to add items to the list
    updateList = (arr) => {
      let blue = document.getElementById("input").value;

      if (blue === "") {
        alert("Please enter a value if you wish to add something to your list.")
      } else {
        arr.push(blue);
        arrayList(myArray); // Re-render the list after adding the item
        idSelector()
      }
      document.getElementById("input").value = ""; // Clear the input field
    }

    //This function is meant to delete the specified item chosen by the user from the shopping list and the array
    deleteItem = (item) => {
      let index = myArray.indexOf(item);
      if (index > -1) {
        myArray.splice(index, 1);
      }
      arrayList(myArray); // Re-render the list after deleting the item
    }
    </script>
</body>

</html>

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注意事项