// JavaScript Document

var current = 1;

function move( eachDiv )
{
current += eachDiv;
if ( current < 1 ) current = 2;
if ( current > 2 ) current = 1;
show( current );
}

function show( oneDiv )
{
current = oneDiv;
for ( var dnum = 1; dnum <= 2; ++dnum )
{
var dv = document.getElementById("div"+dnum);
dv.style.display = ( dnum == oneDiv ? 'block' : 'none' );
}
}