// global variable loaded tests to see if all images are loaded
var loaded = false;

// nameArray holds the names of all the buttons
// should just be able to add a new name and script will take
// care of the rest
var nameArray = new Array('about','director','program','gallery','evolution','funding','involved','sponsor','awards','board','contact','pressroom');

// nameLength holds number in nameArray
var nameLength = nameArray.length;



    // imageArrayOn will hold image object for over state and preload
    var imageArrayOn = new Array();

    // imageArrayOff will hold image object for resting state
    var imageArrayOff = new Array();

    // for preload - set loaded to true when done
    function imageLoad() {

      // make sure we're in a browser that suppports images 
      if (document.images) {
        for (var i=0; i<nameLength; i++) {
            var holder = nameArray[i];
            imageArrayOn[holder] = new Image();
            imageArrayOn[holder].src = 'images/' + holder + '_over.gif';
        }
        for (var i=0; i<nameLength; i++) {
            var holder = nameArray[i];
            imageArrayOff[holder] = new Image();
            imageArrayOff[holder].src = 'images/' + holder + '.gif';
        }
      }
    loaded = true;
    }



// swap the image to the on state
function swapOn(name) {
    if (document.images) {
        if (loaded) {

            document.images[name].src = imageArrayOn[name].src;
        }
    }
}

// swap the image to the resting state
function swapOff(name) {
    if (document.images) {
        if (loaded) {
            document.images[name].src = imageArrayOff[name].src;
        }
    }
}

imageLoad();