[Dilettante_Pro]

Да хоть 100500 штук - скрипт один и тот же.

<div>
   <button value='i1'>Button1</button>
   <button value='i2'>Button2</button>
   <button value='i3'>Button3</button>
   <div id='i1' class='cont' style='display:none'>Content 1</div>
   <div id='i2' class='cont' style='display:none'>Content 2</div>
   <div id='i3' class='cont' style='display:none'>Content 3</div>
</div>
<script>
  [].forEach.call(document.querySelectorAll('button'), function(item) {
        item.onclick = function() {
            [].forEach.call(document.querySelectorAll('.cont'), function(el) {
                el.id == item.value ? el.style.display = 'flex': el.style.display = 'none';
            })
        }
  });
</script>