gistfile1.js

function getNearestTextNode(node, forward) {
	var body = node.ownerDocument.body,
		sibling = forward ? 'nextSibling' : 'previousSibling',
		child = forward ? 'firstChild' : 'lastChild',
		current = node;
	do {
		node = current[sibling], current = node || current.parentNode;
		if (current == body) return;
	}
	while (!node);
	do {
		node = current[child];
		if (!node) {
			if (current.nodeType == 3) return current;
			node = current[sibling];
		}
		if (!node) {
			var tmp = current;
			do {
				node = tmp.parentNode;
				if (node == body) return;
				tmp = node, node = node[sibling];
			}
			while (!node)
		}
		current = node;
	}
	while (current != body);
};