It is necessary after closing the browser, when you open the newly saved all tasks todo.

Website: https://react-todo-app3.vercel.app

Git repository on: https://github.com/paul76546/react-todo-app3

import React, {useState} from 'react';
import TodoForm from './TodoForm';
import Todo from './Todo';
function TodoList () {
 const [todos, setTodos] = useState ([]);
 const addTodo = todo = & gt; {
  if (! todo.text || /^\s*$/.test(todo.text)) {
   Return;
  }
  const newTodos = [todo, ... todos];
  setTodos (newTodos);
  console.log (... todos);
 };
 const updateTodo = (todoId, newValue) = & gt; {
  if (! newValue.text || /^\s*$/.test(newValue.text)) {
   Return;
  }
  setTodos (? prev = & gt; prev.map (item = & gt; (item.id === todoId newValue: item)));
 };
 const removeTodo = id = & gt; {
  const removedArr = [... todos] .filter (todo = & gt; todo.id == id!);
  setTodos (removedArr);
 };
 const completeTodo = id = & gt; {
  let updatedTodos = todos.map (todo = & gt; {
   if (todo.id === id) {
    todo.isComplete = todo.isComplete!;
   }
   return todo;
  });
  setTodos (updatedTodos);
 };
 // h1 heading What are your plans for today?
 // (What's the Plan for Today?) English
 // changing to-do list for today
 // put back
 return (
  & Lt; & gt;
   & Lt; h1 & gt; What's the Plan for Today & lt;? / H1 & gt;
   & Lt; TodoForm onSubmit = {addTodo} / & gt;
   & Lt; Todo
    todos = {todos}
    completeTodo = {completeTodo}
    removeTodo = {removeTodo}
    updateTodo = {updateTodo}
   / & gt;
  & Lt; / & gt;
 );
}
export default TodoList;

Answer 1, Authority 100%

Line initialization state todos remake at:

const [todos, setTodos] = useState (localStorage.getItem ( 'todos')? JSON.parse (localStorage.getItem ( 'todos')): []);

Adding another function (eg: setTodosWithSave):

const setTodosWithSave = (newTodos) = & gt; {
   setTodos (newTodos);
   localStorage.setItem ( 'todos', JSON.stringify (newTodos))
}

The functions of the addTodo, updateTodo, removeTodo, completeTodo change the function setTodos to setTodosWithSave

Answer 2

// import {reactLocalStorage} from 'reactjs-localstorage';
import TodoForm from './TodoForm';
import Todo from './Todo';
function TodoList () {
 // const [todos, setTodos] = useState ([]); for reworking
 const [todos, setTodos] = useState (localStorage.getItem ( 'todos') JSON.parse (localStorage.getItem ( 'todos')): []?);
 // add another function
 const setTodosWithSave = (newTodos) = & gt; {
  setTodos (newTodos);
  localStorage.setItem ( 'todos', JSON.stringify (newTodos))
};
 const addTodo = todo = & gt; {
  if (! todo.text || /^\s*$/.test(todo.text)) {
   Return;
  }
  const newTodos = [todo, ... todos];
  setTodosWithSave (newTodos);
  console.log (... todos);
 };
// in front of the console log was setTodos (newTodos);
 const updateTodo = (todoId, newValue) = & gt; {
  if (! newValue.text || /^\s*$/.test(newValue.text)) {
   Return;
  }
  setTodos (? prev = & gt; prev.map (item = & gt; (item.id === todoId newValue: item)));
 };
// 34 string?
 const removeTodo = id = & gt; {
  const removedArr = [... todos] .filter (todo = & gt; todo.id == id!);
  setTodosWithSave (removedArr);
 };
 const completeTodo = id = & gt; {
  let updatedTodos = todos.map (todo = & gt; {
   if (todo.id === id) {
    todo.isComplete = todo.isComplete!;
   }
   return todo;
  });
  setTodosWithSave (updatedTodos);
 };
 // let toLocal = reactLocalStorage.setObject ( 'var', { 'test': 'test'}); ????? How
 // h1 heading What are your plans for today? 
// (What's the plane for today?) In English
  // I change the list of cases for today
  // I put back
  Return (
   & lt; & gt;
    & lt; h1 & gt; list of cases today & lt; / h1 & gt;
    & lt; todoform onsubmit = {addtodo} / & gt;
    & lt; todo
     TODOS = {TODOS}
     COMPLETETODO = {COMPLETETODO}
     removetodo = {removetodo}
     UpdateTodo = {UpdateToDo}
    / & gt;
   & lt; / & gt;
  );
}
EXPORT DEFAULT TODOLIST;