nextjs 实现TodoList网页应用案例

news2024/10/1 2:01:56

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].completed
    setTodos(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) return
      addTodo(value)
      setValue('')
    }
  
    return (
      <form onSubmit={handleSubmit} className="todo-form">
        <input
          type="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' : ''}`}>
            <input
              type="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;
}