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JavaScript DOM Scripting By Example Editing and Filtering Names Filter Invitees Who Have Not Responded

Carrington Seawright
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Carrington Seawright
Full Stack JavaScript Techdegree Student 8,226 Points

Which line of code assigns li elements the className 'responded' for the' if' condition statement?

The code is working fine but I'm trying to figure out where exactly the line of code is that assigns li elements the 'responded' className so that they are able to be identified in the 'if' statement, nested in the 'for' loop of the 'if(isChecked)' condition.

const form = document.getElementById('registrar');
const input = form.querySelector('input');

const mainDiv = document.querySelector('.main');
const ul = document.getElementById('invitedList');

const div = document.createElement('div');
const filterLabel = document.createElement('label');
const filterCheckBox = document.createElement('input');

filterLabel.textContent = "Hide those who haven't responded";
filterCheckBox.type = 'checkbox';
div.appendChild(filterLabel);
div.appendChild(filterCheckBox);
mainDiv.insertBefore(div, ul);

filterCheckBox.addEventListener('change', (e) =>{
  const isChecked = e.target.checked;
  const lis = ul.children;

  if(isChecked){
    for (let i = 0; i<lis.length; i++){
      let li = lis[i];
      if (li.className === 'responded'){
        li.style.display = '';
      } else {
        li.style.display = 'none';
      }
    }  
  } else {
    for (let i = 0; i<lis.length; i++){
      let li = lis[i];
      li.style.display = '';
    }  
  }
});

function createLI (text){
  const li = document.createElement('li');
  const span = document.createElement('span');
  span.textContent = text;
  li.appendChild(span);
  const label = document.createElement('label');
  label.textContent = 'Confirmed';
  const checkbox = document.createElement('input');
  checkbox.type = 'checkbox';
  label.appendChild(checkbox);
  li.appendChild(label);

  const editButton = document.createElement('button');
  editButton.textContent = 'edit';
  li.appendChild(editButton);

  const removeButton = document.createElement('button');
  removeButton.textContent = 'remove';
  li.appendChild(removeButton);
  return li;
}

form.addEventListener('submit', (e) => {
  e.preventDefault();
  const text = input.value;
  input.value = "";
  const li = createLI(text);
  ul.appendChild(li);
});


ul.addEventListener('change', (e) => {
  const checkbox = event.target;
  const checked = checkbox.checked;
  const listItem = checkbox.parentNode.parentNode;

  if (checked){
    listItem.className = 'responded';
  }else{
    listItem.className = '';
  }
});

ul.addEventListener('click', (e) => {
  if (e.target.tagName == 'BUTTON'){
    const button = e.target;
    const li = button.parentNode;
    const ul = li.parentNode;
    if (button.textContent === 'remove'){
      ul.removeChild(li);
    } else if (button.textContent === 'edit'){
      const span = li.firstElementChild;
      const input = document.createElement('input');
      input.type = 'text';
      input.value = span.textContent;
      li.insertBefore(input, span);
      li.removeChild(span);
      button.textContent = 'save';
    } else if (button.textContent === 'save'){
      const input = li.firstElementChild;
      const newName = document.createElement('span');
      newName.textContent = input.value;
      li.insertBefore(newName, input);
      li.removeChild(input);
      button.textContent = 'edit';
    }
  }
});

There's code that does this within the ul event listener but if i'm correct it's only accessible within that function's scope.

Any help is greatly appreciated.

Best,

ul.addEventListener('change', (e) => {
  const checkbox = event.target;
  const checked = checkbox.checked;
  const listItem = checkbox.parentNode.parentNode;

  if (checked){
    listItem.className = 'responded';
  }else{
    listItem.className = '';
  }
});

In this function the variable being updated is not local variable; it is reference to actual listItem from event.target.parentNode.parentNode Thus value className gets updated for the listItem here.

1 Answer

Steven Parker
Steven Parker
229,920 Points

It's the class name of a DOM element that's being updated, and the entire DOM is global. The local variable, which as you noticed is limited in scope, only serves as a reference to the element while the attribute is being updated.