"DOMContentLoaded" not working for me.

document.addEventListener('DOMContentLoaded ', () => {
  const form = document.getElementById('registrar');
  const input = form.querySelector('input');

  const mainDiv = document.querySelector('.main');
  //const ul...
  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 += 1) {
          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 += 1) {
          let li = lis[i];
          li.style.display = '';
        }
    }
  });


  function createLI(text) {
     //const ul = document.getElementById('invitedList');
    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();
   // console.log(input.value);
    const text = input.value;
    input.value = '';
    //const ul moved to top of file so it can be globally accessible.
   const li = createLI(text);
    ul.appendChild(li);
  });

  //true(checked) and false(unchecked)
  ul.addEventListener('change', (e) => {
    //console.log(e.target.checked);
    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 span = document.createElement('span');
        span.textContent = input.value;
        li.insertBefore(span, input);
        li.removeChild(input);
        button.textContent = 'edit';
      }
  }
  });
}); ```