DOM操作

function parent(e, n){
            var n = n || 1;
            while(n-- && e){
                e = e.parentNode();
            }
            if(!e || e.nodeType != 1){
                return null;
            }
            return e;
        }
        function sibling(e, n){
            while(e && n !==0){
                if(n > 0){
                    if(e.nextElementSibling){
                        e = e.nextElementSibling;
                    } else{
                        for(e = e.nextSibling; e && e.nodeType !== 1; e = e.nextSibling);
                        /*empty loop*/
                    }
                    n--;
                } else{
                    if(e.previousElementSibling){
                        e = e.previousElementSibling;
                    } else{
                        for(e = e.previousSibling; e && e.nodeType !== 1; e = e.previousSibling);
                        /*empty loop*/
                    }
                    n++
                }
            }
            return e;
        }
        function textContent(element, value){
            var content = element.textContent;
            if(value !== undefined){
                if(content !== undefined){
                    content = value;
                } else{
                    element.innerText = value;
                }
            } else{
                if(content !== undefined){
                    return content;
                } else{
                    return element.innerText;
                }
            }
        }
        function textContent(e){
            var child, type, s = '';
            for(child = e.firstChild; child != null; child = child.nextSibling){
                type = child.nodeType;
                if(type == 3 || type == 4){
                    s += child.nodeValue;
                } else if(type == 1){
                    s += textContent(e);
                }
            }
            return s;
        }