diff --git a/lib/$Element.ts b/lib/$Element.ts
index 0acab4d..0edad20 100644
--- a/lib/$Element.ts
+++ b/lib/$Element.ts
@@ -7,6 +7,7 @@ export interface $ElementOptions {
 
 export class $Element<H extends HTMLElement = HTMLElement> extends $Node<H> {
     readonly dom: H;
+    private static_classes = new Set<string>();
     constructor(tagname: string, options?: $ElementOptions) {
         super();
         this.dom = document.createElement(tagname) as H;
@@ -28,17 +29,38 @@ export class $Element<H extends HTMLElement = HTMLElement> extends $Node<H> {
     /**Replace list of class name to element. @example Element.class('name1', 'name2') */
     class(): DOMTokenList;
     class(...name: (string | undefined)[]): this;
-    class(...name: (string | undefined)[]): this | DOMTokenList {return $.fluent(this, arguments, () => this.dom.classList, () => {this.dom.className = ''; this.dom.classList.add(...name.detype())})}
+    class(...name: (string | undefined)[]): this | DOMTokenList {return $.fluent(this, arguments, () => this.dom.classList, () => {this.dom.classList.forEach(n => this.static_classes.has(n) ?? this.dom.classList.remove(n)); this.dom.classList.add(...name.detype())})}
     /**Add class name to dom. */
     addClass(...name: (string | undefined)[]): this {return $.fluent(this, arguments, () => this, () => {this.dom.classList.add(...name.detype())})}
     /**Remove class name from dom */
     removeClass(...name: (string | undefined)[]): this {return $.fluent(this, arguments, () => this, () => {this.dom.classList.remove(...name.detype())})}
 
+    staticClass(): Set<string>;
+    staticClass(...name: (string | undefined)[]): this;
+    staticClass(...name: (string | undefined)[]) {return $.fluent(this, arguments, () => this.static_classes, () => {this.removeClass(...this.static_classes); this.static_classes.clear(); this.addStaticClass(...name);})}
+    addStaticClass(...name: (string | undefined)[]) {return $.fluent(this, arguments, () => this, () => {name.detype().forEach(n => this.static_classes.add(n)); this.addClass(...name)})}
+    removeStaticClass(...name: (string | undefined)[]) {return $.fluent(this, arguments, () => this, () => {name.detype().forEach(n => this.static_classes.delete(n)); this.removeClass(...name)})}
+
     /**Modify css of element. */
     css(): CSSStyleDeclaration
     css(style: Partial<CSSStyleDeclaration>): this;
     css(style?: Partial<CSSStyleDeclaration>) { return $.fluent(this, arguments, () => this.dom.style, () => {Object.assign(this.dom.style, style)})}
     
+    attribute(qualifiedName: string | undefined): string | null;
+    attribute(qualifiedName: string | undefined, value?: string | number | boolean): this;
+    attribute(qualifiedName: string | undefined, value?: string | number | boolean): this | string | null { 
+        if (!arguments.length) return null;
+        if (arguments.length === 1) {
+            if (qualifiedName === undefined) return null;
+            return this.dom.getAttribute(qualifiedName);
+        }
+        if (arguments.length === 2) {
+            if (qualifiedName && value) this.dom.setAttribute(qualifiedName, `${value}`);
+            return this;
+        }
+        return this;
+    }
+    
     autocapitalize(): Autocapitalize;
     autocapitalize(autocapitalize?: Autocapitalize): this;
     autocapitalize(autocapitalize?: Autocapitalize) { return $.fluent(this, arguments, () => this.dom.autocapitalize, () => $.set(this.dom, 'autocapitalize', autocapitalize))}
diff --git a/lib/$Node.ts b/lib/$Node.ts
index 10ca1bc..227fb96 100644
--- a/lib/$Node.ts
+++ b/lib/$Node.ts
@@ -1,10 +1,10 @@
-import { $State, $Text } from "../index";
+import { $Element, $State, $Text } from "../index";
 import { $Container } from "./$Container";
 
 export abstract class $Node<N extends Node = Node> {
     readonly parent?: $Container;
     abstract readonly dom: N;
-    readonly $hidden: boolean = false;
+    readonly __hidden: boolean = false;
     private domEvents: {[key: string]: Map<Function, Function>} = {};
 
     on<K extends keyof HTMLElementEventMap>(type: K, callback: (event: HTMLElementEventMap[K], $node: this) => void, options?: AddEventListenerOptions | boolean) { 
@@ -32,10 +32,10 @@ export abstract class $Node<N extends Node = Node> {
 
     hide(): boolean; 
     hide(hide?: boolean | $State<boolean>): this; 
-    hide(hide?: boolean | $State<boolean>) { return $.fluent(this, arguments, () => this.$hidden, () => {
+    hide(hide?: boolean | $State<boolean>) { return $.fluent(this, arguments, () => this.__hidden, () => {
         if (hide === undefined) return;
-        if (hide instanceof $State) { (this as Mutable<$Node>).$hidden = hide.value; hide.use(this, 'hide')}
-        else (this as Mutable<$Node>).$hidden = hide; 
+        if (hide instanceof $State) { (this as Mutable<$Node>).__hidden = hide.value; hide.use(this, 'hide')}
+        else (this as Mutable<$Node>).__hidden = hide; 
         this.parent?.children.render(); 
         return this;
     })}
@@ -60,8 +60,11 @@ export abstract class $Node<N extends Node = Node> {
     }
 
     self(callback: ($node: this) => void) { callback(this); return this; }
-
     inDOM() { return document.contains(this.dom); }
+    isElement() {
+        if (this instanceof $Element) return this;
+        else return undefined;
+    }
 
     static from(element: HTMLElement | Text): $Node {
         if (element.$) return element.$;
diff --git a/lib/$NodeManager.ts b/lib/$NodeManager.ts
index 8d35ef3..8c2888a 100644
--- a/lib/$NodeManager.ts
+++ b/lib/$NodeManager.ts
@@ -52,13 +52,13 @@ export class $NodeManager {
         while (nodeList.length || domList.length) { // while nodeList or domList has item
             const [node, dom] = [nodeList.at(0), domList.at(0)];
             if (!dom) { if (node && !appendedNodeList.includes(node)) node.remove(); nodeList.shift()} 
-            else if (!node) { if (!dom.$.$hidden) this.#dom.append(dom); domList.shift();}
+            else if (!node) { if (!dom.$.__hidden) this.#dom.append(dom); domList.shift();}
             else if (dom !== node) { 
-                if (!dom.$.$hidden) { this.#dom.insertBefore(dom, node); appendedNodeList.push(dom) }
+                if (!dom.$.__hidden) { this.#dom.insertBefore(dom, node); appendedNodeList.push(dom) }
                 domList.shift();
             }
             else {
-                if (dom.$.$hidden) this.#dom.removeChild(dom);
+                if (dom.$.__hidden) this.#dom.removeChild(dom);
                 domList.shift(); nodeList.shift();
             }
         }
diff --git a/lib/Router/Route.ts b/lib/Router/Route.ts
index 5aa23da..69c4984 100644
--- a/lib/Router/Route.ts
+++ b/lib/Router/Route.ts
@@ -28,17 +28,19 @@ export interface RouteRecord extends $EventMethod<RouteRecordEventMap> {};
 export class RouteRecord {
     id: string;
     readonly content?: $Node;
-    events = new $EventManager<RouteRecordEventMap>().register('open')
+    events = new $EventManager<RouteRecordEventMap>().register('open', 'load')
     constructor(id: string) {
         this.id = id;
     }
 }
 
 export interface RouteRecordEventMap {
-    'open': [path: string, record: RouteRecord]
+    'open': [path: string, record: RouteRecord];
+    'load': [path: string, record: RouteRecord];
 }
 
 export interface RouteRequest<Path extends PathResolverFn | string> {
     params: PathParamResolver<Path>,
     record: RouteRecord,
+    loaded: () => void;
 }
\ No newline at end of file
diff --git a/lib/Router/Router.ts b/lib/Router/Router.ts
index 7476683..9a19acd 100644
--- a/lib/Router/Router.ts
+++ b/lib/Router/Router.ts
@@ -9,7 +9,7 @@ export class Router {
     recordMap = new Map<string, RouteRecord>();
     view: $Container;
     index: number = 0;
-    events = new $EventManager<RouterEventMap>().register('pathchange', 'notfound');
+    events = new $EventManager<RouterEventMap>().register('pathchange', 'notfound', 'load');
     basePath: string;
     constructor(basePath: string, view: $Container) {
         this.basePath = basePath;
@@ -26,7 +26,7 @@ export class Router {
     /**Start listen to the path change */
     listen() {
         if (!history.state || 'index' in history.state === false) {
-            const routeData: RouteData = {index: this.index}
+            const routeData: RouteData = {index: this.index, data: {}}
             history.replaceState(routeData, '')
         } else {
             this.index = history.state.index
@@ -39,10 +39,11 @@ export class Router {
     }
 
     /**Open path */
-    open(path: string) {
+    open(path: string | undefined) {
+        if (path === undefined) return;
         if (path === location.href) return this;
         this.index += 1;
-        const routeData: RouteData = { index: this.index };
+        const routeData: RouteData = { index: this.index, data: {} };
         history.pushState(routeData, '', path);
         $.routers.forEach(router => router.resolvePath())
         this.events.fire('pathchange', path, 'Forward');
@@ -59,6 +60,12 @@ export class Router {
         return this;
     }
 
+    setStateData(key: string, value: any) {
+        if (history.state.data === undefined) history.state.data = {};
+        history.state.data[key] = value;
+        return this;
+    }
+
     private popstate = (() => {
         // Forward
         if (history.state.index > this.index) { }
@@ -77,8 +84,7 @@ export class Router {
             const record = this.recordMap.get(pathId);
             if (record) {
                 found = true;
-                if (record.content && this.view.contains(record.content)) return true;
-                this.view.content(record.content);
+                if (record.content && !this.view.contains(record.content)) this.view.content(record.content);
                 record.events.fire('open', path, record);
                 return true;
             }
@@ -86,7 +92,14 @@ export class Router {
         }
         const create = (pathId: string, route: Route<any>, data: any) => {
             const record = new RouteRecord(pathId);
-            let content = route.builder({params: data, record: record});
+            let content = route.builder({
+                params: data, 
+                record: record, 
+                loaded: () => {
+                    record.events.fire('load', pathId, record);
+                    this.events.fire('load', pathId);
+                }
+            });
             if (typeof content === 'string') content = new $Text(content);
             (record as Mutable<RouteRecord>).content = content;
             this.recordMap.set(pathId, record);
@@ -134,10 +147,11 @@ export class Router {
 }
 interface RouterEventMap {
     pathchange: [path: string, navigation: 'Back' | 'Forward'];
-    notfound: [path: string]
+    notfound: [path: string];
+    load: [path: string];
 }
 
 type RouteData = {
     index: number;
-    data?: any;
+    data: {[key: string]: any};
 }
\ No newline at end of file