diff --git a/examples/hello-world/src/App.tsx b/examples/hello-world/src/App.tsx
index ac455c1..08e9d72 100644
--- a/examples/hello-world/src/App.tsx
+++ b/examples/hello-world/src/App.tsx
@@ -1 +1 @@
-export {default} from './memo'
+export {default} from './fragment'
diff --git a/examples/hello-world/src/fragment/index.tsx b/examples/hello-world/src/fragment/index.tsx
new file mode 100644
index 0000000..258c857
--- /dev/null
+++ b/examples/hello-world/src/fragment/index.tsx
@@ -0,0 +1,19 @@
+import {useState} from 'react'
+
+export default function App() {
+  const [num, setNum] = useState(100)
+  const arr =
+    num % 2 === 0
+      ? [<li key='1'>1</li>, <li key='2'>2</li>, <li key='3'>3</li>]
+      : [<li key='3'>3</li>, <li key='2'>2</li>, <li key='1'>1</li>]
+  return (
+    <ul onClick={() => setNum((num) => num + 1)}>
+      {/* <li>4</li>
+      <li>5</li> */}
+      {arr}
+      <span>{num}</span>
+
+      {/* {num} */}
+    </ul>
+  )
+}
diff --git a/packages/react-reconciler/src/begin_work.rs b/packages/react-reconciler/src/begin_work.rs
index fac3c81..bea6426 100644
--- a/packages/react-reconciler/src/begin_work.rs
+++ b/packages/react-reconciler/src/begin_work.rs
@@ -121,9 +121,16 @@ pub fn begin_work(
             render_lane.clone(),
         )),
         WorkTag::MemoComponent => update_memo_component(work_in_progress.clone(), render_lane),
+        WorkTag::Fragment => Ok(update_fragment(work_in_progress.clone())),
     };
 }
 
+fn update_fragment(work_in_progress: Rc<RefCell<FiberNode>>) -> Option<Rc<RefCell<FiberNode>>> {
+    let next_children = work_in_progress.borrow().pending_props.clone();
+    reconcile_children(work_in_progress.clone(), Some(next_children));
+    work_in_progress.borrow().child.clone()
+}
+
 fn update_memo_component(
     work_in_progress: Rc<RefCell<FiberNode>>,
     render_lane: Lane,
diff --git a/packages/react-reconciler/src/child_fiber.rs b/packages/react-reconciler/src/child_fiber.rs
index 4d938ee..c90cfb9 100644
--- a/packages/react-reconciler/src/child_fiber.rs
+++ b/packages/react-reconciler/src/child_fiber.rs
@@ -6,7 +6,7 @@ use std::rc::Rc;
 use wasm_bindgen::{JsCast, JsValue};
 use web_sys::js_sys::{Array, Object, Reflect};
 
-use shared::{derive_from_js_value, log, type_of, REACT_ELEMENT_TYPE};
+use shared::{derive_from_js_value, log, type_of, REACT_ELEMENT_TYPE, REACT_FRAGMENT_TYPE};
 
 use crate::fiber::FiberNode;
 use crate::fiber_flags::Flags;
@@ -133,7 +133,15 @@ fn reconcile_single_element(
         }
     }
 
-    let mut fiber = FiberNode::create_fiber_from_element(element);
+    let mut fiber ;
+    if derive_from_js_value(&element, "type") == REACT_FRAGMENT_TYPE {
+        let props = derive_from_js_value(&element, "props");
+        let children = derive_from_js_value(&props, "children");
+        fiber = FiberNode::create_fiber_from_fragment(children, key);
+    } else {
+        fiber = FiberNode::create_fiber_from_element(element);
+    }
+   
     fiber._return = Some(return_fiber.clone());
     Rc::new(RefCell::new(fiber))
 }
@@ -205,6 +213,26 @@ impl Hash for Key {
     }
 }
 
+fn update_fragment(
+    return_fiber: Rc<RefCell<FiberNode>>,
+    current: Option<Rc<RefCell<FiberNode>>>,
+    elements: JsValue,
+    key: Key,
+    existing_children: &mut HashMap<Key, Rc<RefCell<FiberNode>>>,
+) -> Rc<RefCell<FiberNode>> {
+    let fiber;
+    if current.is_none() || current.clone().unwrap().borrow().tag != WorkTag::Fragment {
+        fiber = Rc::new(RefCell::new(FiberNode::create_fiber_from_fragment(
+            elements, key.0,
+        )));
+    } else {
+        existing_children.remove(&key);
+        fiber = use_fiber(current.clone().unwrap(), elements);
+    }
+    fiber.borrow_mut()._return = Some(return_fiber);
+    fiber
+}
+
 fn update_from_map(
     return_fiber: Rc<RefCell<FiberNode>>,
     existing_children: &mut HashMap<Key, Rc<RefCell<FiberNode>>>,
@@ -250,31 +278,58 @@ fn update_from_map(
                 JsValue::null(),
             ))))
         };
+    } else if element.is_array() {
+        let before = match before {
+            Some(before) => Some((*before).clone()),
+            None => None,
+        };
+        return Some(update_fragment(
+            return_fiber,
+            before,
+            (*element).clone(),
+            Key(key_to_use.clone()),
+            existing_children,
+        ));
     } else if type_of(element, "object") && !element.is_null() {
-        if derive_from_js_value(&(*element).clone(), "$$typeof") != REACT_ELEMENT_TYPE {
-            panic!("Undefined $$typeof");
-        }
-
-        if before.is_some() {
-            let before = (*before.clone().unwrap()).clone();
-            existing_children.remove(&Key(key_to_use.clone()));
-            if Object::is(
-                &before.borrow()._type,
-                &derive_from_js_value(&(*element).clone(), "type"),
-            ) {
-                return Some(use_fiber(
-                    before.clone(),
-                    derive_from_js_value(element, "props"),
+        if derive_from_js_value(&(*element).clone(), "$$typeof") == REACT_ELEMENT_TYPE {
+            if derive_from_js_value(&(*element).clone(), "type") == REACT_FRAGMENT_TYPE {
+                let before = match before {
+                    Some(before) => Some((*before).clone()),
+                    None => None,
+                };
+                return Some(update_fragment(
+                    return_fiber,
+                    before,
+                    (*element).clone(),
+                    Key(key_to_use.clone()),
+                    existing_children,
                 ));
-            } else {
-                delete_child(return_fiber, before, should_track_effects);
             }
-        }
 
-        return Some(Rc::new(RefCell::new(FiberNode::create_fiber_from_element(
-            element,
-        ))));
+            if before.is_some() {
+                let before = (*before.clone().unwrap()).clone();
+                existing_children.remove(&Key(key_to_use.clone()));
+                if Object::is(
+                    &before.borrow()._type,
+                    &derive_from_js_value(&(*element).clone(), "type"),
+                ) {
+                    return Some(use_fiber(
+                        before.clone(),
+                        derive_from_js_value(element, "props"),
+                    ));
+                }
+
+                // else {
+                //     delete_child(return_fiber, before, should_track_effects);
+                // }
+            }
+
+            return Some(Rc::new(RefCell::new(FiberNode::create_fiber_from_element(
+                element,
+            ))));
+        }
     }
+
     None
 }
 
diff --git a/packages/react-reconciler/src/commit_work.rs b/packages/react-reconciler/src/commit_work.rs
index ea5f388..f0c437a 100644
--- a/packages/react-reconciler/src/commit_work.rs
+++ b/packages/react-reconciler/src/commit_work.rs
@@ -494,8 +494,8 @@ fn get_host_parent(fiber: Rc<RefCell<FiberNode>>) -> Option<Rc<RefCell<FiberNode
 fn get_host_sibling(fiber: Rc<RefCell<FiberNode>>) -> Option<Rc<dyn Any>> {
     let mut node = Some(fiber);
     'find_sibling: loop {
-        let node_rc = node.clone().unwrap();
-        while node_rc.borrow().sibling.is_none() {
+        while node.clone().unwrap().borrow().sibling.is_none() {
+            let node_rc = node.clone().unwrap();
             let parent = node_rc.borrow()._return.clone();
             let tag = parent.clone().unwrap().borrow().tag.clone();
             if parent.is_none() || tag == HostComponent || tag == HostRoot {
@@ -515,9 +515,10 @@ fn get_host_sibling(fiber: Rc<RefCell<FiberNode>>) -> Option<Rc<dyn Any>> {
             ._return = _return;
         node = node_rc.borrow().sibling.clone();
 
-        let node_rc = node.clone().unwrap();
-        let tag = node_rc.borrow().tag.clone();
-        while tag != HostText && tag != HostComponent {
+        while node.clone().unwrap().borrow().tag != HostText
+            && node.clone().unwrap().borrow().tag != HostComponent
+        {
+            let node_rc = node.clone().unwrap();
             if node_rc.borrow().flags.contains(Flags::Placement) {
                 continue 'find_sibling;
             }
diff --git a/packages/react-reconciler/src/fiber.rs b/packages/react-reconciler/src/fiber.rs
index dcffed3..a566141 100644
--- a/packages/react-reconciler/src/fiber.rs
+++ b/packages/react-reconciler/src/fiber.rs
@@ -78,17 +78,6 @@ pub struct FiberNode {
 impl Debug for FiberNode {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         Ok(match self.tag {
-            WorkTag::FunctionComponent => {
-                write!(
-                    f,
-                    "{:?}(flags:{:?}, subtreeFlags:{:?}, lanes:{:?})",
-                    self._type.as_ref(),
-                    self.flags,
-                    self.subtree_flags,
-                    self.lanes
-                )
-                .expect("print error");
-            }
             WorkTag::HostRoot => {
                 write!(
                     f,
@@ -98,18 +87,10 @@ impl Debug for FiberNode {
                 )
                 .expect("print error");
             }
-            WorkTag::HostComponent => {
-                write!(
-                    f,
-                    "{:?}(key:{:?}, flags:{:?}, subtreeFlags:{:?})",
-                    self._type, self.key, self.flags, self.subtree_flags
-                )
-                .expect("print error");
-            }
             WorkTag::HostText => {
                 write!(
                     f,
-                    "{:?}(state_node:{:?}, flags:{:?})",
+                    "{:?}(state_node:{:?},flags:{:?})",
                     self.tag,
                     Reflect::get(self.pending_props.as_ref(), &JsValue::from_str("content"))
                         .unwrap(),
@@ -117,25 +98,17 @@ impl Debug for FiberNode {
                 )
                 .expect("print error");
             }
-            WorkTag::ContextProvider => {
-                write!(
-                    f,
-                    "{:?}(flags:{:?}, subtreeFlags:{:?}, lanes:{:?})",
-                    self._type.as_ref(),
-                    self.flags,
-                    self.subtree_flags,
-                    self.lanes
-                )
-                .expect("print error");
-            }
-            WorkTag::MemoComponent => {
+            _ => {
                 write!(
                     f,
-                    "{:?}(flags:{:?}, subtreeFlags:{:?}, lanes:{:?})",
+                    "{:?}(tag:{:?},key:{:?}flags:{:?},subtreeFlags:{:?},lanes:{:?},childLanes:{:?})",
                     self._type.as_ref(),
+                    self.tag,
+                    self.key,
                     self.flags,
                     self.subtree_flags,
-                    self.lanes
+                    self.lanes,
+                    self.child_lanes
                 )
                 .expect("print error");
             }
@@ -169,6 +142,10 @@ impl FiberNode {
         }
     }
 
+    pub fn create_fiber_from_fragment(elements: JsValue, key: JsValue) -> FiberNode {
+        FiberNode::new(WorkTag::Fragment, elements, key, JsValue::null())
+    }
+
     pub fn create_fiber_from_element(ele: &JsValue) -> Self {
         let _type = derive_from_js_value(ele, "type");
         let key = derive_from_js_value(ele, "key");
@@ -396,7 +373,7 @@ impl Debug for FiberRootNode {
                     }
 
                     if current_ref._return.is_some() {
-                        write!(f, ",").expect("print error");
+                        write!(f, " | ").expect("print error");
                     } else {
                         writeln!(f, "").expect("print error");
                         writeln!(f, "------------------------------------").expect("print error");
diff --git a/packages/react-reconciler/src/fiber_hooks.rs b/packages/react-reconciler/src/fiber_hooks.rs
index 67b8a92..0557bcb 100644
--- a/packages/react-reconciler/src/fiber_hooks.rs
+++ b/packages/react-reconciler/src/fiber_hooks.rs
@@ -407,7 +407,7 @@ fn update_state(_: &JsValue) -> Result<Vec<JsValue>, JsValue> {
             base_state: new_base_state,
             base_queue: new_base_queue,
         } = process_update_queue(
-            base_state,
+            base_state.clone(),
             base_queue,
             unsafe { RENDER_LANE.clone() },
             Some(|update: Rc<RefCell<Update>>| {
@@ -474,19 +474,10 @@ fn dispatch_set_state(
     let lane = request_update_lane();
     let mut update = create_update(action.clone(), lane.clone());
     let current = { fiber.borrow().alternate.clone() };
-    log!(
-        "dispatch_set_state {:?} {:?}",
-        fiber.borrow().lanes.clone(),
-        if current.is_none() {
-            Lane::NoLane
-        } else {
-            current.clone().unwrap().borrow().lanes.clone()
-        }
-    );
+    log!("dispatch_set_state action:{:?}", action);
     if fiber.borrow().lanes == Lane::NoLane
         && (current.is_none() || current.unwrap().borrow().lanes == Lane::NoLane)
     {
-        log!("sdadgasd");
         let current_state = update_queue.borrow().last_rendered_state.clone();
         if current_state.is_none() {
             panic!("current state is none")
diff --git a/packages/react-reconciler/src/work_loop.rs b/packages/react-reconciler/src/work_loop.rs
index 0f710e9..87ce5c9 100644
--- a/packages/react-reconciler/src/work_loop.rs
+++ b/packages/react-reconciler/src/work_loop.rs
@@ -72,12 +72,12 @@ pub fn mark_update_lane_from_fiber_to_root(
         let p = parent.clone().unwrap();
         let child_lanes = { p.borrow().child_lanes.clone() };
         p.borrow_mut().child_lanes = merge_lanes(child_lanes, lane.clone());
-
         let alternate = p.borrow().alternate.clone();
         if alternate.is_some() {
             let alternate = alternate.unwrap();
             let child_lanes = { alternate.borrow().child_lanes.clone() };
             alternate.borrow_mut().child_lanes = merge_lanes(child_lanes, lane.clone());
+            log!("mark_update_lane_from_fiber_to_root alternate {:?}", p);
         }
 
         node = parent.clone().unwrap();
@@ -198,8 +198,8 @@ fn render_root(root: Rc<RefCell<FiberRootNode>>, lanes: Lane, should_time_slice:
         };
     }
 
-    // log!("render over {:?}", *root.clone().borrow());
-    log!("render over {:?}", unsafe { WORK_IN_PROGRESS.clone() });
+    log!("render over {:?}", *root.clone().borrow());
+    // log!("render over {:?}", unsafe { WORK_IN_PROGRESS.clone() });
     // log!("render over");
 
     unsafe {
diff --git a/packages/react-reconciler/src/work_tags.rs b/packages/react-reconciler/src/work_tags.rs
index cfecddf..5bc9754 100644
--- a/packages/react-reconciler/src/work_tags.rs
+++ b/packages/react-reconciler/src/work_tags.rs
@@ -4,6 +4,7 @@ pub enum WorkTag {
     HostRoot = 3,
     HostComponent = 5,
     HostText = 6,
+    Fragment = 7,
     ContextProvider = 8,
     MemoComponent = 15,
 }
diff --git a/packages/react/src/lib.rs b/packages/react/src/lib.rs
index 800d31b..4a30bdf 100644
--- a/packages/react/src/lib.rs
+++ b/packages/react/src/lib.rs
@@ -171,7 +171,7 @@ pub unsafe fn create_context(default_value: &JsValue) -> JsValue {
 }
 
 #[wasm_bindgen]
-pub unsafe fn memo(_type: &JsValue, compare: &JsValue) -> JsValue {
+pub fn memo(_type: &JsValue, compare: &JsValue) -> JsValue {
     let fiber_type = Object::new();
 
     Reflect::set(
diff --git a/packages/shared/src/lib.rs b/packages/shared/src/lib.rs
index e0c65ab..8e7dee8 100644
--- a/packages/shared/src/lib.rs
+++ b/packages/shared/src/lib.rs
@@ -6,6 +6,7 @@ pub static REACT_ELEMENT_TYPE: &str = "react.element";
 pub static REACT_CONTEXT_TYPE: &str = "react.context";
 pub static REACT_PROVIDER_TYPE: &str = "react.provider";
 pub static REACT_MEMO_TYPE: &str = "react.memo";
+pub static REACT_FRAGMENT_TYPE: &str = "react.fragment";
 
 #[macro_export]
 macro_rules! log {
diff --git a/scripts/build.js b/scripts/build.js
index 5d231d0..b552538 100644
--- a/scripts/build.js
+++ b/scripts/build.js
@@ -70,3 +70,17 @@ fs.writeFileSync(
     ? 'const {updateDispatcher} = require("react");\n'
     : 'import {updateDispatcher} from "react";\n') + reactDomIndexBgData
 )
+
+// add Fragment
+const reactIndexFilename = `${cwd}/dist/react/jsx-dev-runtime.js`
+const reactIndexData = fs.readFileSync(reactIndexFilename)
+fs.writeFileSync(
+  reactIndexFilename,
+  reactIndexData + `export const Fragment='react.fragment';\n`
+)
+const reactTsIndexFilename = `${cwd}/dist/react/jsx-dev-runtime.d.ts`
+const reactTsIndexData = fs.readFileSync(reactTsIndexFilename)
+fs.writeFileSync(
+  reactTsIndexFilename,
+  reactTsIndexData + `export const Fragment: string;\n`
+)