>If I have this line:
>
>

>el.style.visibility=(el.style.visibility=="visible") ? "hidden" : "visible"
>

>
>How can I make it more easy to understand such as splitting it into a normal IF condition?

What is the problem?

if (el.style.visibility == "visible)
   el.style.visibility = "hidden"
else
  el.style.visibility = "visible"

Not tested, but looks OK to me.