Question

我有一个使用JavaScript的待办事项应用程序，可以根据其功能添加，删除条目。但是，一旦单击了“编辑”按钮，只有第一项可以响应，而其他项则无济于事。

如何使其响应并在此处进行编辑。

这是我的代码：

// Define UI Vars
const form = document.querySelector('#task-form');
const taskList = document.querySelector('.collection');
const clearBtn = document.querySelector('.clear-tasks');
const filter = document.querySelector('#filter');
const taskInput = document.querySelector('#task');
const editList = null;

// Load all event listeners
loadEventListeners();

// Load all event listeners
function loadEventListeners() {
  // Add task event
  form.addEventListener('submit', addTask);
  // Remove task event
  taskList.addEventListener('click', removeTask);

   //edit task
//
  // Clear task event
  clearBtn.addEventListener('click', clearTasks);
  // Filter tasks event
  filter.addEventListener('keyup', filterTasks);

}


// Add Task
function addTask(e) {
  if(taskInput.value === '') {
    alert('Add a task');
  }

  // Create li element
  const li = document.createElement('li');
  // Add class
  li.className = 'collection-item';
  // Create text node and append to li
  li.appendChild(document.createTextNode(taskInput.value));
  // Create new link element
  const link = document.createElement('a');

  // Add class
  link.className = 'delete-item secondary-content';
  // Add icon html
  link.innerHTML = '<i class="fa fa-remove"></i>';

  // Append the link to li
  li.appendChild(link);


  // Append li to ul
  taskList.appendChild(li);

  const editButton=document.createElement("button");//edit button
  editButton.className="editbtn";
  editButton.innerText="Edit";//innerText encodes special characters, HTML does not.
  li.appendChild(editButton);
  taskList.appendChild(editButton);
  const editList = document.querySelector('.editbtn');
  editList.addEventListener('click',editTask)

  // Clear input
  taskInput.value = '';

  e.preventDefault();
}

// Remove Task
function removeTask(e) {
  if(e.target.parentElement.classList.contains('delete-item')) {
    if(confirm('Are You Sure?')) {
      e.target.parentElement.parentElement.remove();
    }
  }
}

// Clear Tasks
function clearTasks() {
  // taskList.innerHTML = '';

  // Faster
  while(taskList.firstChild) {
    taskList.removeChild(taskList.firstChild);
  }

  // https://jsperf.com/innerhtml-vs-removechild
}


// Filter Tasks
function filterTasks(e) {
  const text = e.target.value.toLowerCase();

  document.querySelectorAll('.collection-item').forEach(function(task){
    const item = task.firstChild.textContent;
    if(item.toLowerCase().indexOf(text) != -1){
      task.style.display = 'block';
    } else {
      task.style.display = 'none';
    }
  });
}

function editTask (e) {
   console.log('clicked')
}

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/materialize/0.100.2/css/materialize.min.css">
  <link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet" integrity="sha384-wvfXpqpZZVQGK6TAh5PVlGOfQNHSoD2xbE+QkPxCAFlNEevoEH3Sl0sibVcOQVnN" crossorigin="anonymous">
  <title>Task List</title>
</head>
<body>
  <div class="container">
    <div class="row">
      <div class="col s12">
        <div id="main" class="card">
          <div class="card-content">
            <span class="card-title">Task List</span>
            <div class="row">
              <form id="task-form">
                <div class="input-field col s12">
                  <input type="text" name="task" id="task">
                  <label for="task">New Task</label>
                </div>
                <input type="submit" value="Add Task" class="btn">
              </form>
            </div>
          </div>
          <div class="card-action">
            <h5 id="task-title">Tasks</h5>
            <div class="input-field col s12">
              <input type="text" name="filter" id="filter">
              <label for="filter">Filter Tasks</label>
            </div>
            <ul class="collection"></ul>
            <a href="#" class="clear-tasks btn black">Clear Tasks</a>
          </div>
        </div>
      </div>
    </div>
  </div>

  <script
  src="https://code.jquery.com/jquery-3.2.1.js"
  integrity="sha256-DZAnKJ/6XZ9si04Hgrsxu/8s717jcIzLy3oi35EouyE="
  crossorigin="anonymous"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/materialize/0.100.2/js/materialize.min.js"></script>
  <script src="app.js"></script>
</body>
</html>

感谢您阅读我的问题

致谢

Answer 1

因为const editList = document.querySelector('.editbtn');正在选择找到的第一个按钮并添加点击。它不是选择您刚刚添加的按钮。因此，第一个元素不是多次触发该功能，因为您不断向它添加越来越多的事件侦听器。

您已经具有对该按钮的引用，因此无需查找它。

editButton.addEventListener('click', editTask)

Answer 2

document.querySelector()返回第一个匹配的元素。每次您调用此querySelector()时，它将返回第一个编辑按钮。直接addEventListener到editButton，而不是从querySelector()

调用

 editButton.addEventListener('click',editTask)

为什么第二个按钮在这里什么也不做？

2 个答案: