帖子中的查看全部 折叠内容怎么搞的？

<script>
	function foldFold(floor) {
		var content = document.getElementById('floor_content_' + floor);
		var foldBar = document.getElementById('floor_fold_bar_' + floor);
		
		content.style.maxHeight = '768px';
		foldBar.innerHTML = '<a id="floor_expand_' + floor +
				'" href="#" onclick="foldExpand(' + floor + ');return false">查看全部</a>';
	}
	
	function foldExpand(floor) {
		var content = document.getElementById('floor_content_' + floor);
		var foldBar = document.getElementById('floor_fold_bar_' + floor);
		
		content.style.maxHeight = '';
		foldBar.innerHTML = '<a id="floor_fold_' + floor +
				'" href="#" onclick="foldFold(' + floor + ');return false">折叠内容</a>';
	}
	
	function foldFloorInit(floor) {
		var content = document.getElementById('floor_content_' + floor);
		var height = content.offsetHeight;
		
		if (height > 768) {
			var foldBar = document.getElementById('floor_fold_bar_' + floor);
			
			foldBar.style.borderTop = '1px solid #BED8EA';
			foldBar.style.borderBottom = '1px solid #BED8EA';
			foldBar.style.height = '24px';
			foldBar.style.textAlign = 'center';
			
			foldFold(floor);
		}
	}
	
	function foldFloorOnload(floorSize) {
		var i;
		
		for (i=0; i<floorSize; i++) {
			foldFloorInit(i);
		}
	}
</script>
<script>
    function atAdd(uid,that) {
        that.style.color = "#FFA500";
        var nr = document.getElementById("content");
        nr.value += "@"+uid+"，";
    }
</script>
		<div class="floor_content" id="floor_content_0">
[文章正文.....]
</div>
		<div class="floor_fold_bar" id="floor_fold_bar_0"></div>
		<script>foldFloorInit(0)</script>