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JavaScript

Posted by Donna Lorenzo
Donna Lorenzo
Courses Plus Student 7,150 Points

Guil's Up and Down Button Challenge

Hello Treehouse Community,

I need your help explaining what is happening in a section of my code. I think I solved Guil's challenge by mistake. I created a function that hides the buttons and called the function in the event listener. What i don't understand is why do the buttons stay in place if I call the function inside event and if I call the function outside they move. Thank you very much in advance! 

// Hides unused buttons
  function hideUnusedButtons() {
  let firstListItem = listUl.firstElementChild;
  let lastListItem = listUl.lastElementChild;
  firstListItem.firstElementChild.style.visibility = 'hidden';
  lastListItem.querySelector('.down').style.visibility = 'hidden';

  for (let i = 0; i < lis.length; i++) {
    if(lis[i] !== firstListItem) {
      lis[i].firstElementChild.style.visibility = 'visible';
    }
    if(lis[i] !== lastListItem) {
      lis[i].querySelector('.down').style.visibility = 'visible';
    }
  }
}

// Moves items up and down and removes them
listUl.addEventListener('click', (event) => {

  if (event.target.tagName == 'BUTTON') {

    if (event.target.className == 'remove') {
      let li = event.target.parentNode;
      let ul = li.parentNode;
      ul.removeChild(li);
    }

    if (event.target.className == 'up') {
      let li = event.target.parentNode;
      let prevLi = li.previousElementSibling;
      let ul = li.parentNode;
      if (prevLi !== null) { // Checking to see if Li has a previous element
        ul.insertBefore(li, prevLi);
      } 
    }
    if (event.target.className == 'down') {
      let li = event.target.parentNode;
      let nextLi = li.nextElementSibling;
      let ul = li.parentNode;
      if (nextLi !== null) { // Checking to see if Li has an after element
        ul.insertBefore(nextLi, li);
      }
    }
  }
  hideUnusedButtons();
});