Change variable if an element is visible in javascript/jquery

Question

I'm trying to find a way to change a variable if a specific element is visible using JavaScript/jQuery. Here is my code:

function showSlides(n) {
  var i;
  var slides = null;
  if (!$('#elementA').is(':visible')) {
    slides = document.getElementsByClassName("setA")
  }
  else if (!$('#elementB').is(':visible')) {
    slides = document.getElementsByClassName("setB")
  }
  if (n > slides.length) {slideIndex = 1}
  if (n < 1) {slideIndex = slides.length}
  for (i = 0; i < slides.length; i++) {
    slides[i].style.display = "none";
  }
  slides[slideIndex-1].style.display = "block";
}

Resuming, if element A is visible, I want to change the variable 'slides' to find all elements with the class '.setA'. Then it makes a slideshow out of all divs found with that class. If element A is not visible, I want my code to check if element B is visible and if so, change the variable 'slides' to find all elements with the class '.setB' etc.

The code works if I specify 'slides' without using 'if'.

I am quite new to this, can you help me out?

Answer 1

According to your question the code must be as follows.

if ($('#elementA').is(':visible')) {
    slides = document.getElementsByClassName("setA")
}
if ($('#elementB').is(':visible')) {
    slides = document.getElementsByClassName("setB")
}

There is no use of !.