https://public.resource.org/js/toggle.js

1function toggleVisibility(id, NNtype, IEtype, WC3type) {
2    if (document.getElementById) {
3        eval("document.getElementById(id).style.visibility = \"" + WC3type + "\"");
4    } else {
5        if (document.layers) {
6            document.layers[id].visibility = NNtype;
7        } else {
8            if (document.all) {
9                eval("document.all." + id + ".style.visibility = \"" + IEtype + "\"");
10            }
11        }
12    }
13}
14
15function ChangeZ(id) {
16obj = document.getElementById("existingLayerID");
17if (typeof obj!="undefined")
18{
19 obj.style.zIndex=50;
20}
21}
22
23function tOn(id) {
24   toggleVisibility(id, "show", "visible", "visible") ;
25   }
26function tOff(id) {
27   toggleVisibility(id, 'hidden', 'hidden', 'hidden') ;
28   }