var ids = new Array('indexmenu','ratesmenu','ssmenu','progmenu','aboutmenu','hoursmenu');

function switchid(id){
    hideallids();
    showdiv(id);
}

function hideallids(){
//loop through the array and hide each element by id
    for (var i=0; i < ids.length; i++){
        hidediv(ids[i]);
    }  
}

function hidediv(id) {
//safe function to hide an element with a specified id
    var element = document.getElementById(id);
    if(element) {
        element.style.display = 'none';
    }
}

function showdiv(id) {
//safe function to show an element with a specified id
    var element = document.getElementById(id);
    if(element) {
        element.style.display = 'block';
    }
}

hideallids();