HTML Academy
Deleting the element from the list
Working with DOM5/23
Back to the list of tasks
  • 1. What are you planning to do?
  • 2. The “change” event
  • 3. How the “change” event works
  • 4. Deleting the element from the list
  • 5. How to check the collection length
  • 6. Debugging the code
  • 7. Static and live collections
  • 8. Displaying the message on the page
  • 9. The “submit” event
  • 10. Cancelling the form submission
  • 11. How to obtain text from the input field
  • 12. Templates and the <template> tag
  • 13. The contents of the <template> tag, document-fragment
  • 14. Cloning and inserting elements, part 1
  • 15. Cloning and inserting elements, part 2
  • 16. Cloning and inserting elements, part 3
  • 17. Cloning and inserting elements, part 4
  • 18. How to clone elements
  • 19. Adding a new element to a list
  • 20. Deleting a new task in the list
  • 21. Clearing the input field
  • 22. Summary of “Actions with DOM”
  • 23. The third program: “Instant messenger”
Debugging the code
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  • Theory
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How to check the collection length

The completed goals have been removed from the to-do list! Let’s proceed to the next item in our job specification:

  • A task is considered completed and disappears if the user clicks the checkbox.
  • If all of the tasks are completed, then a message should be displayed informing the user that there are no more tasks.
  • If a new task is added to an empty list, the message disappears.
  • To add a new task, you must enter a description in the input field and press “Add task”. The task will then appear at the end of the list.

All of the tasks will be completed when all of the elements are deleted from the list list. Now all of the tasks are located in the items collection, and its length is equal to the number of li elements in the list. If the tasks are deleted, then the collection length will be equal to 0. And then you can show the message.

For the moment, we do not need to find a message that there are no tasks in the markup and to try to show it. First, let’s make sure that the collection length is actually decreasing. In order to do this, create a function that will check the length (by the way, we have already added the function declaration to the code for you). We will call this function every time after we remove a task.

In this assignment, we will use strict equality to avoid unpredictable results. A strict equality is written as: === (three equal signs). If you have forgotten what this type of equality signifies and why it is used, look at this assignment, where we discussed it.

Comments

  • index.html
  • style.css
  • script.js
HTML
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <title>The To-Do List</title> <link href="style.css" rel="stylesheet"> </head> <body> <h1 class="visually-hidden">The To-Do List</h1> <ul class="todo-list"> <li class="todo-list-item"> <label> <input class="todo-list-input" type="checkbox"> <span>Feed the cat</span> </label> </li> <li class="todo-list-item"> <label> <input class="todo-list-input" type="checkbox"> <span>Leave the country</span> </label> </li> <li class="todo-list-item"> <label> <input class="todo-list-input" type="checkbox"> <span>Go for a run</span> </label> </li> </ul> <p class="empty-tasks hidden">All of the tasks have been completed. There are no new tasks.</p> <form class="add-form" action="https://echo.htmlacademy.ru/courses" method="post"> <input class="add-form-input" type="text" aria-label="Task description" placeholder="For example, buy an elephant" required> <button class="add-form-button" type="submit">Add new task</button> </form> <template id="task-template"> <li class="todo-list-item"> <label> <input type="checkbox" class="todo-list-input"> <span></span> </label> </li> </template> <script src="script.js"></script> </body> </html>
CSS
@font-face { font-weight: 400; font-family: "Muller"; font-style: normal; font-display: swap; src: url("fonts/Muller.woff") format("woff"); } body { margin: 40px 32px; font-size: 18px; line-height: normal; font-family: "Muller", sans-serif; } .visually-hidden, .todo-list-input { position: absolute; width: 1px; height: 1px; margin: -1px; padding: 0; overflow: hidden; white-space: nowrap; border: 0; clip: rect(0 0 0 0); clip-path: inset(100%); } .hidden { display: none; } .todo-list { margin: 0; padding: 0; list-style: none; } .todo-list-item { margin-bottom: 12px; } .todo-list-item label { display: block; padding: 12px 18px; background-color: #ffffff; border-radius: 4px; box-shadow: 0 2px 5px rgba(0, 0, 0, 0.15); cursor: pointer; user-select: none; } .todo-list-item span { display: flex; align-items: center; } .todo-list-input + span::before { content: ""; display: inline-block; width: 16px; height: 16px; margin-right: 16px; background-color: #ffffff; border: 2px solid #69b253; border-radius: 4px; } .todo-list-input:checked + span::before { background-color: #69b253; background-image: url("check-white.svg"); background-repeat: no-repeat; background-position: center; } .todo-list-input:not(:checked):hover + span::before, .todo-list-input:not(:checked):focus + span::before { background-color: rgba(105, 178, 83, 0.2); } .empty-tasks { color: #69b253; } .empty-tasks::before { content: ""; width: 14px; height: 13px; margin-right: 13px; background-image: url("check-green.svg"); background-repeat: no-repeat; background-position: center; } .add-form { display: flex; } .add-form-input { flex-grow: 1; box-sizing: border-box; height: 46px; margin-right: 16px; padding: 12px; font: inherit; border: 1px solid #a1b5c4; border-radius: 4px; } .add-form-input:focus { border: 1px solid #69b253; outline: none; } .add-form-input:hover { box-shadow: 0 0 6px rgba(105, 178, 83, 0.6); } .add-form-input::placeholder { color: #a1b5c4; } .add-form-button { flex-shrink: 0; padding: 12px; font: inherit; color: #ffffff; background-color: #69b253; border: none; border-radius: 4px; user-select: none; touch-action: manipulation; } .add-form-button:hover, .add-form-button:focus { background-color: #5aa045; outline: none; } .add-form-button:active { background-color: #42862e; }
JavaScript
var list = document.querySelector('.todo-list'); var items = list.querySelectorAll('.todo-list-item'); var toggleEmptyListMessage = function () { // Write a check here }; var addCheckHandler = function (item) { var checkbox = item.querySelector('.todo-list-input'); checkbox.addEventListener('change', function () { item.remove(); }); }; for (var i = 0; i < items.length; i++) { addCheckHandler(items[i]); }

What didn’t you like in this task?

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Console
Goalscompleted
0
    1. Add a check in the body of the toggleEmptyListMessage function that verifies that the items collection length is equal to 0. Use a strict equality.
    2. Inside the condition, output the string 'All of the goals are completed!' to the console.
    3. In the body of the addCheckHandler function, inside the handler, after the element is removed, call the toggleEmptyListMessage function.
    4. Mark all of the goals as completed in the mini-browser, and look at the console output. The result could surprise you.

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