nextjs 实现TodoList网页应用案例

参考：
https://nextjs.org/

Next.js 是用于网络的一种 React 框架。一些世界上最大的公司在使用它，它能够借助 React 组件的力量让您创建高质量的网络应用程序。

1、创建项目：

另外注意：pages与app路由存在冲突，如果有app文件夹删除，比如这里创建的就用src下面app文件夹，整体删除，不然构建项目会报错

npx create-next-app@latest todolist
cd todolist

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2、创建组件、页面
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pages目录下创建index.js

import { useState, useEffect } from 'react'
import TodoForm from '../components/TodoForm'
import TodoList from '../components/TodoList'export default function Home() {const [todos, setTodos] = useState([])useEffect(() => {const storedTodos = JSON.parse(localStorage.getItem('todos') || '[]')setTodos(storedTodos)}, [])useEffect(() => {localStorage.setItem('todos', JSON.stringify(todos))}, [todos])const addTodo = (text) => {setTodos([{ text, completed: false }, ...todos])}const toggleTodo = (index) => {const newTodos = [...todos]newTodos[index].completed = !newTodos[index].completedsetTodos(newTodos)}const deleteTodo = (index) => {const newTodos = todos.filter((_, i) => i !== index)setTodos(newTodos)}return (<div className="container"><h1>TodoList</h1><TodoForm addTodo={addTodo} /><TodoList todos={todos} toggleTodo={toggleTodo} deleteTodo={deleteTodo} /></div>)
}

pages目录下创建_app.js

import '../styles/globals.css'function MyApp({ Component, pageProps }) {return <Component {...pageProps} />
}export default MyApp

在components目录下创建TodoForm.js

import { useState } from 'react'export default function TodoForm({ addTodo }) {const [value, setValue] = useState('')const handleSubmit = (e) => {e.preventDefault()if (!value) returnaddTodo(value)setValue('')}return (<form onSubmit={handleSubmit} className="todo-form"><inputtype="text"value={value}onChange={(e) => setValue(e.target.value)}placeholder="Add a todo"/><button type="submit">Add</button></form>)}

在components目录下创建TodoList.js:

export default function TodoList({ todos, toggleTodo, deleteTodo }) {return (<ul className="todo-list">{todos.map((todo, index) => (<li key={index} className={`todo-item ${todo.completed ? 'completed' : ''}`}><inputtype="checkbox"checked={todo.completed}onChange={() => toggleTodo(index)}/><span>{todo.text}</span><button onClick={() => deleteTodo(index)}>Delete</button></li>))}</ul>)}

在styles目录下的globals.css中添加样式

body {font-family: Arial, sans-serif;max-width: 500px;margin: 0 auto;padding: 20px;
}h1 {text-align: center;
}.todo-form {display: flex;margin-bottom: 20px;
}.todo-form input {flex-grow: 1;padding: 10px;font-size: 16px;border: 1px solid #ddd;border-radius: 4px 0 0 4px;
}.todo-form button {padding: 10px 20px;font-size: 16px;background-color: #4CAF50;color: white;border: none;border-radius: 0 4px 4px 0;cursor: pointer;
}.todo-list {list-style-type: none;padding: 0;
}.todo-item {display: flex;align-items: center;padding: 10px;background-color: #f9f9f9;border: 1px solid #ddd;margin-bottom: 10px;border-radius: 4px;
}.todo-item.completed {text-decoration: line-through;opacity: 0.6;
}.todo-item input[type="checkbox"] {margin-right: 10px;
}.todo-item button {margin-left: auto;background-color: #f44336;color: white;border: none;padding: 5px 10px;border-radius: 4px;cursor: pointer;
}