Function not defined javascript

The actual problem is with your

showList function.

There is an extra ')' after ‘visible’.

Remove that and it will work fine.

function showList()
{
  if (document.getElementById("favSports").style.visibility == "hidden") 
    {
       // document.getElementById("favSports").style.visibility = "visible");  
       // your code
       document.getElementById("favSports").style.visibility = "visible";
       // corrected code
    }
}