diff --git a/.gitignore b/.gitignore
new file mode 100644
index 00000000..496ee2ca
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.DS_Store
\ No newline at end of file
diff --git a/README.md b/README.md
index 502436de..0e28256a 100644
--- a/README.md
+++ b/README.md
@@ -39,15 +39,15 @@
 
 ## 🎯 요구사항
 
-- [ ] todo list에 todoItem을 키보드로 입력하여 추가하기
-- [ ] todo list의 체크박스를 클릭하여 complete 상태로 변경 (li tag 에 completed class 추가, input 태그에 checked 속성 추가)
-- [ ] todo list의 x버튼을 이용해서 해당 엘리먼트를 삭제
-- [ ] todo list를 더블클릭했을 때 input 모드로 변경 (li tag 에 editing class 추가) 단 이때 수정을 완료하지 않은 상태에서 esc키를 누르면 수정되지 않은 채로 다시 view 모드로 복귀
-- [ ] todo list의 item갯수를 count한 갯수를 리스트의 하단에 보여주기
-- [ ] todo list의 상태값을 확인하여, 해야할 일과, 완료한 일을 클릭하면 해당 상태의 아이템만 보여주기
+- [x] todo list에 todoItem을 키보드로 입력하여 추가하기
+- [x] todo list의 체크박스를 클릭하여 complete 상태로 변경 (li tag 에 completed class 추가, input 태그에 checked 속성 추가)
+- [x] todo list의 x버튼을 이용해서 해당 엘리먼트를 삭제
+- [x] todo list를 더블클릭했을 때 input 모드로 변경 (li tag 에 editing class 추가) 단 이때 수정을 완료하지 않은 상태에서 esc키를 누르면 수정되지 않은 채로 다시 view 모드로 복귀
+- [x] todo list의 item갯수를 count한 갯수를 리스트의 하단에 보여주기
+- [x] todo list의 상태값을 확인하여, 해야할 일과, 완료한 일을 클릭하면 해당 상태의 아이템만 보여주기
 
 ## 🎯🎯 심화 요구사항
-- [ ] localStorage에 데이터를 저장하여, TodoItem의 CRUD를 반영하기. 따라서 새로고침하여도 저장된 데이터를 확인할 수 있어야 함
+- [x] localStorage에 데이터를 저장하여, TodoItem의 CRUD를 반영하기. 따라서 새로고침하여도 저장된 데이터를 확인할 수 있어야 함
 
 <br/>
 
diff --git a/index.html b/index.html
index 13a02fdb..c94ff217 100644
--- a/index.html
+++ b/index.html
@@ -34,5 +34,6 @@ <h1>TODOS</h1>
         </div>
       </main>
     </div>
+    <script src="./src/index.js" type="module"></script>
   </body>
 </html>
diff --git a/src/App.js b/src/App.js
new file mode 100644
index 00000000..1cadb75a
--- /dev/null
+++ b/src/App.js
@@ -0,0 +1,13 @@
+import TodoInput from "./components/TodoInput.js";
+import TodoList from "./components/TodoList/index.js";
+import TodoTotal from "./components/TodoTotal.js";
+import TodoFilters from "./components/TodoFilters.js";
+
+import { $ } from "./utils/selectors.js";
+
+export default function App(store) {
+  store.addObserver(new TodoInput(store, $(".new-todo")));
+  store.addObserver(new TodoList(store, $(".todo-list")));
+  store.addObserver(new TodoTotal(store, $(".todo-count")));
+  store.addObserver(new TodoFilters(store, $(".filters")));
+}
diff --git a/src/components/TodoFilters.js b/src/components/TodoFilters.js
new file mode 100644
index 00000000..8067291b
--- /dev/null
+++ b/src/components/TodoFilters.js
@@ -0,0 +1,22 @@
+import { buildViewState } from "../utils/helpers.js";
+import { $, isInClassList } from "../utils/selectors.js";
+
+export default class TodoList {
+  constructor(store, $app) {
+    this.store = store;
+    this.$app = $app;
+    this.mount();
+  }
+  mount() {
+    this.$app.addEventListener("click", (e) => {
+      const isAll = isInClassList("all", e.target);
+      const isActive = isInClassList("active", e.target);
+      const isCompleted = isInClassList("completed", e.target);
+      const hash = e.target.hash ? e.target.hash.substring(1) : "all";
+      if (isAll || isActive || isCompleted) {
+        buildViewState(hash, this.store, e);
+      }
+    });
+  }
+  render() {}
+}
diff --git a/src/components/TodoInput.js b/src/components/TodoInput.js
new file mode 100644
index 00000000..a1f1d2f1
--- /dev/null
+++ b/src/components/TodoInput.js
@@ -0,0 +1,26 @@
+const CIPHER = 1000;
+
+export default class TodoInput {
+  constructor(store, $app) {
+    this.store = store;
+    this.$app = $app;
+    this.mount();
+  }
+  mount() {
+    this.$app.addEventListener("keypress", this.handleInputValue.bind(this));
+  }
+  render() {}
+  handleInputValue(e) {
+    if (e.key === "Enter") {
+      const prevState = this.store.getState();
+      const newTodo = {
+        id: Math.floor(Math.random() * CIPHER),
+        content: e.target.value,
+        status: "active",
+      };
+      const newState = { ...prevState, todos: [...prevState.todos, newTodo] };
+      this.store.setState(newState);
+      e.target.value = "";
+    }
+  }
+}
diff --git a/src/components/TodoList/constant.js b/src/components/TodoList/constant.js
new file mode 100644
index 00000000..e938e41e
--- /dev/null
+++ b/src/components/TodoList/constant.js
@@ -0,0 +1,8 @@
+export const TOGGLE = "toggle";
+export const DELETE = "delete";
+export const EDIT = "edit";
+export const EDITING = "editing";
+export const DESTROY = "destroy";
+export const COMPLETED = "completed";
+export const CHECKED = "checked";
+export const FALSE = "false";
diff --git a/src/components/TodoList/helper.js b/src/components/TodoList/helper.js
new file mode 100644
index 00000000..338e23ab
--- /dev/null
+++ b/src/components/TodoList/helper.js
@@ -0,0 +1,88 @@
+//prettier-ignore
+import { TOGGLE, DESTROY, DELETE, EDITING, EDIT } from "./constant.js";
+import { filterTodos } from "../../utils/helpers.js";
+import { $, isInClassList } from "../../utils/selectors.js";
+
+//MOUNT HELPER
+export function toggleTodoItem(e, store) {
+  const isToggle = isInClassList(TOGGLE, e.target);
+  if (isToggle) {
+    buildNewState(TOGGLE, store, e);
+  }
+}
+export function deleteTodoItem(e, store) {
+  const isDestroy = isInClassList(DESTROY, e.target);
+  if (isDestroy) {
+    buildNewState(DELETE, store, e);
+  }
+}
+export function setEditingMode(e) {
+  const isList = e.target.closest("li");
+  if (isList) {
+    isList.classList.add(EDITING);
+  }
+}
+export function editSelectedTodo(e, store) {
+  const isEditing = isInClassList(EDIT, e.target);
+  if (isEditing && e.key === "Enter") {
+    buildNewState(EDIT, store, e);
+    e.target.closest("li").classList.remove(EDITING);
+  }
+  if (isEditing && e.key === "Escape") {
+    const currentValue = $(".label").textContent;
+    e.target.value = currentValue;
+    e.target.closest("li").classList.remove(EDITING);
+  }
+}
+
+//VIEW HELPER
+export function buildListTodos(store) {
+  const { todos, view } = store.getState();
+  return view === "all" ? todos : filterTodos(todos, view);
+}
+
+//STATE HELPER
+function buildNewState(op, store, e) {
+  const OPERATIONS = {
+    toggle: toggleTodoStatus,
+    delete: deleteTodo,
+    edit: editTodo,
+  };
+  const prevState = store.getState();
+  const targetId = Number(e.target.closest("li").getAttribute("dataset-id"));
+
+  const newTodos = OPERATIONS[op](prevState, targetId, e);
+
+  const newState = { ...prevState, todos: newTodos };
+  store.setState(newState);
+}
+
+//TODO - STATUS
+function toggleTodoStatus(prevState, targetId, e) {
+  const newStatus = e.target.checked ? "completed" : "active";
+  const newTodos = prevState.todos.map((todo) => {
+    if (todo.id === targetId) {
+      return { ...todo, status: newStatus };
+    }
+    return todo;
+  });
+  return newTodos;
+}
+//TODO - DELETE
+function deleteTodo(prevState, targetId) {
+  const newTodos = prevState.todos.filter((todo) => {
+    return todo.id !== targetId;
+  });
+  return newTodos;
+}
+
+//TODO - UPDATE
+function editTodo(prevState, targetId, e) {
+  const newTodos = prevState.todos.map((todo) => {
+    if (todo.id === targetId) {
+      return { ...todo, content: e.target.value };
+    }
+    return todo;
+  });
+  return newTodos;
+}
diff --git a/src/components/TodoList/index.js b/src/components/TodoList/index.js
new file mode 100644
index 00000000..54c19969
--- /dev/null
+++ b/src/components/TodoList/index.js
@@ -0,0 +1,34 @@
+//prettier-ignore
+import { buildListTodos, editSelectedTodo, toggleTodoItem, deleteTodoItem, setEditingMode } from "./helper.js";
+import { COMPLETED, CHECKED, FALSE } from "./constant.js";
+
+export default class TodoList {
+  constructor(store, $app) {
+    this.store = store;
+    this.$app = $app;
+    this.mount();
+    this.render();
+  }
+  mount() {
+    //prettier-ignore
+    this.$app.addEventListener("keydown", (e) => editSelectedTodo(e, this.store));
+    this.$app.addEventListener("dblclick", (e) => setEditingMode(e));
+    this.$app.addEventListener("click", (e) => toggleTodoItem(e, this.store));
+    this.$app.addEventListener("click", (e) => deleteTodoItem(e, this.store));
+  }
+  render() {
+    this.$app.innerHTML = buildListTodos(this.store)
+      .map(({ id, content, status, edit }) => {
+        const isChecked = status === COMPLETED ? CHECKED : FALSE;
+        return `<li dataset-id=${id} class="${status} ${edit}">
+                  <div class="view">
+                    <input class="toggle" type="checkbox" ${isChecked}>
+                    <label class="label">${content}</label>
+                    <button class="destroy" ></button>
+                  </div>
+                  <input class="edit" value="${content}">
+                </li>`;
+      })
+      .join("");
+  }
+}
diff --git a/src/components/TodoTotal.js b/src/components/TodoTotal.js
new file mode 100644
index 00000000..acf1e141
--- /dev/null
+++ b/src/components/TodoTotal.js
@@ -0,0 +1,15 @@
+import { filterTodos } from "../utils/helpers.js";
+
+export default class TodoTotal {
+  constructor(store, $app) {
+    this.store = store;
+    this.$app = $app;
+  }
+  render() {
+    const { view, todos } = this.store.getState();
+    //prettier-ignore
+    const curViewTodos = view === "all" ? todos 
+                                        : filterTodos(todos, view);
+    this.$app.innerHTML = `총 <strong>${curViewTodos.length}</strong> 개</span>`;
+  }
+}
diff --git a/src/index.js b/src/index.js
new file mode 100644
index 00000000..41df63f9
--- /dev/null
+++ b/src/index.js
@@ -0,0 +1,3 @@
+import App from "./App.js";
+import Store from "./store/index.js";
+new App(new Store());
diff --git a/src/storage/index.js b/src/storage/index.js
new file mode 100644
index 00000000..0e47664d
--- /dev/null
+++ b/src/storage/index.js
@@ -0,0 +1,4 @@
+export const get = (key, defaultState) =>
+  JSON.parse(localStorage.getItem(key)) || defaultState;
+export const set = (key, newState) =>
+  localStorage.setItem(key, JSON.stringify(newState));
diff --git a/src/store/index.js b/src/store/index.js
new file mode 100644
index 00000000..0d76fb32
--- /dev/null
+++ b/src/store/index.js
@@ -0,0 +1,25 @@
+import { get, set } from "../storage/index.js";
+const USER = "user";
+
+export default class Store {
+  constructor() {
+    this.state = get(USER, { todos: [], view: "all" });
+    this.observers = [];
+  }
+  addObserver(observer) {
+    this.observers.push(observer);
+  }
+  observing() {
+    this.observers.forEach((observer) => observer.render());
+  }
+  //GET
+  getState() {
+    return this.state;
+  }
+  //SET
+  setState(newState) {
+    this.state = { ...this.state, ...newState };
+    set(USER, this.state);
+    this.observing();
+  }
+}
diff --git a/src/utils/constants.js b/src/utils/constants.js
new file mode 100644
index 00000000..31dd86be
--- /dev/null
+++ b/src/utils/constants.js
@@ -0,0 +1,10 @@
+export const TOGGLE = "toggle";
+export const DELETE = "delete";
+export const EDIT = "edit"
+export const EDITING = "editing"
+export const DESTORY = "destory"
+export const ENTER = "Enter"
+export const ESCAPE = "Escape"
+export const COMPLETED = "completed"
+export const CHECKED = "checked"
+export const FALSE = 'false'
\ No newline at end of file
diff --git a/src/utils/helpers.js b/src/utils/helpers.js
new file mode 100644
index 00000000..72b72441
--- /dev/null
+++ b/src/utils/helpers.js
@@ -0,0 +1,16 @@
+import { $ } from "./selectors.js";
+
+export function buildViewState(op, store, e) {
+  $(".selected").classList.remove("selected");
+  e.target.className = `${op} selected`;
+
+  const state = store.getState();
+  const newState = { ...state, view: op };
+  store.setState(newState);
+}
+
+export function filterTodos(todos, view) {
+  return todos.filter((todo) => {
+    if (todo.status === view) return todo;
+  });
+}
diff --git a/src/utils/selectors.js b/src/utils/selectors.js
new file mode 100644
index 00000000..e8b4ad8d
--- /dev/null
+++ b/src/utils/selectors.js
@@ -0,0 +1,3 @@
+export const $ = (node) => document.querySelector(node);
+export const $all = (node) => document.querySelectorAll(node)
+export const isInClassList = (tagName, eventTarget) => eventTarget.classList.contains(tagName)
\ No newline at end of file