http://www.raychem.com/content/dam/te-com/custom/javascript/raychem/raychem-de.js

1    var DDSPEED = 10;
2    var DDTIMER = 15;
3     
4    // main function to handle the mouse events //
5    function ddMenu(id,d){
6    var h = document.getElementById(id + '-ddheader');
7    var c = document.getElementById(id + '-ddcontent');
8    clearInterval(c.timer);
9    if(d == 1){
10    clearTimeout(h.timer);
11    if(c.maxh && c.maxh <= c.offsetHeight){return}
12    else if(!c.maxh){
13    c.style.display = 'block';
14    c.style.height = 'auto';
15    c.maxh = c.offsetHeight;
16    c.style.height = '0px';
17    }
18    c.timer = setInterval(function(){ddSlide(c,1)},DDTIMER);
19    }else{
20    h.timer = setTimeout(function(){ddCollapse(c)},50);
21    }
22    }
23     
24    // collapse the menu //
25    function ddCollapse(c){
26    c.timer = setInterval(function(){ddSlide(c,-1)},DDTIMER);
27    }
28     
29    // cancel the collapse if a user rolls over the dropdown //
30    function cancelHide(id){
31    var h = document.getElementById(id + '-ddheader');
32    var c = document.getElementById(id + '-ddcontent');
33    clearTimeout(h.timer);
34    clearInterval(c.timer);
35    if(c.offsetHeight < c.maxh){
36    c.timer = setInterval(function(){ddSlide(c,1)},DDTIMER);
37    }
38    }
39     
40    // incrementally expand/contract the dropdown and change the opacity //
41    function ddSlide(c,d){
42    var currh = c.offsetHeight;
43    var dist;
44    if(d == 1){
45    dist = (Math.round((c.maxh - currh) / DDSPEED));
46    }else{
47    dist = (Math.round(currh / DDSPEED));
48    }
49    if(dist <= 1 && d == 1){
50    dist = 1;
51    }
52    c.style.height = currh + (dist * d) + 'px';
53    c.style.opacity = currh / c.maxh;
54    c.style.filter = 'alpha(opacity=' + (currh * 100 / c.maxh) + ')';
55    if((currh < 2 && d != 1) || (currh > (c.maxh - 2) && d == 1)){
56    clearInterval(c.timer);
57    }
58    }