How to change the style of elements with same class name

Question

Using javascript, I want to change the style of class .s into

.s {
  display: block;
}

Why this cannot work:

Answer 1

As getElementsByClassName returns an array you need to make a for loop over all found elements:

var elements = document.getElementsByClassName('s');
for (var i = 0; i < elements.length; i++) {
    elements[i].style.display = "block";
}