React Props 完整使用指南

1. 类组件中的 Props

1.1 基本使用

// 父组件
class ParentComponent extends React.Component {
  render() {
    return (
      <ChildComponent 
        name="John"
        age={25}
        isStudent={true}
        hobbies={['reading', 'swimming']}
      />
    );
  }
}

// 子组件
class ChildComponent extends React.Component {
  render() {
    const { name, age, isStudent, hobbies } = this.props;
    return (
      <div>
        <h2>Name: {name}</h2>
        <p>Age: {age}</p>
        <p>Is Student: {isStudent ? 'Yes' : 'No'}</p>
        <ul>
          {hobbies.map(hobby => (
            <li key={hobby}>{hobby}</li>
          ))}
        </ul>
      </div>
    );
  }
}

1.2 默认 Props

class Welcome extends React.Component {
  render() {
    return <h1>Hello, {this.props.name}</h1>;
  }
}

Welcome.defaultProps = {
  name: 'Guest'
};

// 或者使用静态属性
class Welcome extends React.Component {
  static defaultProps = {
    name: 'Guest'
  };
  
  render() {
    return <h1>Hello, {this.props.name}</h1>;
  }
}

1.3 Props 类型检查

import PropTypes from 'prop-types';

class User extends React.Component {
  render() {
    return (
      <div>
        <h1>{this.props.name}</h1>
        <p>Age: {this.props.age}</p>
      </div>
    );
  }
}

User.propTypes = {
  name: PropTypes.string.isRequired,
  age: PropTypes.number,
  email: PropTypes.string,
  friends: PropTypes.arrayOf(PropTypes.string),
  address: PropTypes.shape({
    street: PropTypes.string,
    city: PropTypes.string
  })
};

1.4 Props 作为方法传递

class ParentComponent extends React.Component {
  handleClick = (data) => {
    console.log('Clicked:', data);
  }

  render() {
    return <ChildComponent onClick={this.handleClick} />;
  }
}

class ChildComponent extends React.Component {
  render() {
    return (
      <button onClick={() => this.props.onClick('Hello')}>
        Click me
      </button>
    );
  }
}

2. 函数组件中的 Props

2.1 基本使用

// 解构方式接收 props
function Welcome({ name, age }) {
  return (
    <div>
      <h1>Hello, {name}</h1>
      <p>Age: {age}</p>
    </div>
  );
}

// 直接接收 props 对象
function Welcome(props) {
  return (
    <div>
      <h1>Hello, {props.name}</h1>
      <p>Age: {props.age}</p>
    </div>
  );
}

// 使用组件
function App() {
  return <Welcome name="John" age={25} />;
}

2.2 默认 Props

// 使用默认参数
function Welcome({ name = 'Guest' }) {
  return <h1>Hello, {name}</h1>;
}

// 或者使用 defaultProps
function Welcome(props) {
  return <h1>Hello, {props.name}</h1>;
}

Welcome.defaultProps = {
  name: 'Guest'
};

2.3 Props 类型检查

import PropTypes from 'prop-types';

function User({ name, age, email, friends, address }) {
  return (
    <div>
      <h1>{name}</h1>
      <p>Age: {age}</p>
      <p>Email: {email}</p>
      <ul>
        {friends.map(friend => (
          <li key={friend}>{friend}</li>
        ))}
      </ul>
      <p>
        Address: {address.street}, {address.city}
      </p>
    </div>
  );
}

User.propTypes = {
  name: PropTypes.string.isRequired,
  age: PropTypes.number,
  email: PropTypes.string,
  friends: PropTypes.arrayOf(PropTypes.string),
  address: PropTypes.shape({
    street: PropTypes.string,
    city: PropTypes.string
  })
};

2.4 Props 作为回调函数

function ParentComponent() {
  const handleClick = (data) => {
    console.log('Clicked:', data);
  };

  return <ChildComponent onClick={handleClick} />;
}

function ChildComponent({ onClick }) {
  return (
    <button onClick={() => onClick('Hello')}>
      Click me
    </button>
  );
}

3. Props 高级用法

3.1 Children Props

// 类组件
class Container extends React.Component {
  render() {
    return (
      <div className="container">
        {this.props.children}
      </div>
    );
  }
}

// 函数组件
function Container({ children }) {
  return (
    <div className="container">
      {children}
    </div>
  );
}

// 使用
function App() {
  return (
    <Container>
      <h1>Title</h1>
      <p>Content</p>
    </Container>
  );
}

3.2 Render Props

class MouseTracker extends React.Component {
  state = { x: 0, y: 0 };

  handleMouseMove = (event) => {
    this.setState({
      x: event.clientX,
      y: event.clientY
    });
  };

  render() {
    return (
      <div onMouseMove={this.handleMouseMove}>
        {this.props.render(this.state)}
      </div>
    );
  }
}

// 使用
function App() {
  return (
    <MouseTracker
      render={({ x, y }) => (
        <h1>鼠标位置: {x}, {y}</h1>
      )}
    />
  );
}

3.3 Props 转发

// 使用 React.forwardRef
const FancyButton = React.forwardRef((props, ref) => (
  <button ref={ref} className="fancy-button">
    {props.children}
  </button>
));

// 使用组件
function App() {
  const buttonRef = React.useRef();
  
  return <FancyButton ref={buttonRef}>Click me!</FancyButton>;
}

4. Props 最佳实践

4.1 命名约定

使用驼峰命名法
布尔值 props 使用 is/has 前缀
事件处理函数使用 handle/on 前缀

function UserProfile({
  isActive,
  hasPermission,
  onNameChange,
  handleSubmit
}) {
  // ...
}

4.2 解构和默认值

function UserCard({
  name = 'Guest',
  age = 0,
  avatar = 'default.png',
  ...otherProps
}) {
  return (
    <div {...otherProps}>
      <img src={avatar} alt={name} />
      <h2>{name}</h2>
      <p>Age: {age}</p>
    </div>
  );
}

4.3 TypeScript 中的 Props

interface UserProps {
  name: string;
  age: number;
  email?: string;
  onUpdate: (id: number) => void;
}

// 函数组件
function User({ name, age, email, onUpdate }: UserProps) {
  return (
    <div>
      <h1>{name}</h1>
      <p>Age: {age}</p>
      {email && <p>Email: {email}</p>}
      <button onClick={() => onUpdate(1)}>Update</button>
    </div>
  );
}

// 类组件
class User extends React.Component<UserProps> {
  render() {
    const { name, age, email, onUpdate } = this.props;
    return (
      <div>
        <h1>{name}</h1>
        <p>Age: {age}</p>
        {email && <p>Email: {email}</p>}
        <button onClick={() => onUpdate(1)}>Update</button>
      </div>
    );
  }
}

5. 性能优化

5.1 React.memo

const MemoizedComponent = React.memo(function MyComponent(props) {
  // 只在 props 改变时重新渲染
  return (
    <div>{props.value}</div>
  );
});

5.2 shouldComponentUpdate

class OptimizedComponent extends React.Component {
  shouldComponentUpdate(nextProps) {
    return this.props.value !== nextProps.value;
  }

  render() {
    return <div>{this.props.value}</div>;
  }
}