How do i make a javascript fuction repeat every few seconds?

Question

 function showdiv(){
document.getElementById("divexample").style.visibility="visible";
 }
 setTimeout("showdiv()", 0); 
 function hidediv()
 { document.getElementById("divexample").style.visibility="hidden";
 }
 setTimeout("hidediv()", 12000);    

Im wondering how i could make that code repeat after every few seconds. Its meant to display some text and hide it but i want it to repeat this action