解构赋值使用方法全面详解与实例解析

// 交换变量值
let a = 1;
let b = 2;
[a, b] = [b, a];
console.log(a, b); // 2 1

// 获取函数返回的多个值
function getStats() {
  return [100, 200, 300];
}

const [min, max, avg] = getStats();
console.log(min, max, avg); // 100 200 300

// 解构字符串
const [firstChar, ...restChars] = "Hello";
console.log(firstChar); // H
console.log(restChars); // ['e', 'l', 'l', 'o']

// 深层嵌套解构
const settings = {
  theme: "dark",
  notifications: {
    email: true,
    sms: false
  }
};

const {
  theme,
  notifications: { email: emailNotif }
} = settings;

console.log(theme, emailNotif); // dark true

// 解构时重命名与默认值结合
const { 
  title: bookTitle = "Unknown", 
  author: bookAuthor = "Anonymous" 
} = { title: "JavaScript Advanced" };

console.log(bookTitle, bookAuthor); // JavaScript Advanced Anonymous

// 函数参数解构与默认值
function createUser({ 
  name = "Guest", 
  age = 18, 
  role = "user" 
} = {}) {
  return { name, age, role };
}

console.log(createUser()); // { name: 'Guest', age: 18, role: 'user' }
console.log(createUser({ name: "Alice", role: "admin" })); // { name: 'Alice', age: 18, role: 'admin' }

// 从函数返回值解构
function calculate(a, b) {
  return {
    sum: a + b,
    difference: a - b,
    product: a * b
  };
}

const { sum, product } = calculate(5, 3);
console.log(sum, product); // 8 15

// 基础组件
function UserProfile({ 
  name, 
  age, 
  avatar = "default.png", 
  onEdit = () => {} 
}) {
  return (
    <div className="user-profile">
      <img src={avatar} alt={name} />
      <h2>{name}</h2>
      <p>Age: {age}</p>
      <button onClick={onEdit}>Edit</button>
    </div>
  );
}

// 使用时解构
const user = {
  name: "Bob",
  age: 28,
  avatar: "bob.jpg"
};

<UserProfile {...user} onEdit={() => console.log("Editing...")} />

export default {
  props: {
    user: {
      type: Object,
      required: true
    }
  },
  computed: {
    // 解构user对象
    ...mapState({
      ...mapState({
        username: state => state.user.name,
        userAge: state => state.user.age
      })
    })
  }
}

// FormInput.jsx
const FormInput = ({
  label,
  type = "text",
  placeholder,
  value,
  onChange,
  required = false,
  disabled = false,
  className = ""
}) => {
  return (
    <div className={`form-group ${className}`}>
      <label htmlFor={label}>{label}</label>
      <input
        type={type}
        id={label}
        placeholder={placeholder}
        value={value}
        onChange={onChange}
        required={required}
        disabled={disabled}
      />
    </div>
  );
};

// 使用示例
<FormInput
  label="Email"
  type="email"
  placeholder="Enter your email"
  value={email}
  onChange={handleEmailChange}
  required
/>

// 封装一个带配置项的模态框组件
const Modal = ({
  title = "Confirm Action",
  message = "Are you sure?",
  confirmText = "Confirm",
  cancelText = "Cancel",
  onConfirm,
  onCancel,
  show = false,
  className = ""
}) => {
  return (
    show && (
      <div className={`modal ${className}`}>
        <div className="modal-content">
          <h3>{title}</h3>
          <p>{message}</p>
          <div className="modal-actions">
            <button onClick={onCancel}>{cancelText}</button>
            <button onClick={onConfirm}>{confirmText}</button>
          </div>
        </div>
      </div>
    )
  );
};

interface User {
  name: string;
  age?: number;
  role: string;
}

function displayUser({ name, age = 0, role }: User) {
  console.log(`${name} (${age}) - ${role}`);
}

// 性能优化示例
const users = [/* 大量用户数据 */];

// 避免每次循环都解构
for (const user of users) {
  const { id, name } = user; // 缓存解构结果
  // 处理逻辑
}