React 受控组件&非受控组件（4）

受控组件是通过绑定事件的方式，及时获取组件状态的变化，适合即时的数据验证非受控组件是通过 React.createRef 创建的引用来获取需要的元素(状态)，灵活性更高，开发者可以在需要时随时调用

受控组件

const hobbiesData = [
  {
    name: "钢琴",
    value: "piano",
  },
  {
    name: "读书",
    value: "read",
  },
  {
    name: "游泳",
    value: "swiming",
  },
];

class App extends React.Component {
  state = {
    username: "",
    sex: "meal",
    isStudent: true,
    hobbies: [],
  };

  handleChange(e) {
    this.setState({
      [e.target.name]: e.target.value,
    });
  }
  handleStuChange(isStudent) {
    this.setState({
      isStudent,
    });
  }

  handleHobbiesChange(e) {
    console.log(111, e.target.value);
    this.setState({
      hobbies: [...this.state.hobbies, e.target.value],
    });
  }

  submit() {
    console.log(this.state);
  }
  reset() {
    this.setState({
      username: "",
      sex: "meal",
    });
  }

  render() {
    const { username, sex, isStudent, hobbies } = this.state;
    return (
      <div>
        <p>
          <span>用户名：</span>
          <input
            type="text"
            name="username"
            value={username}
            onChange={this.handleChange.bind(this)}
          />
        </p>

        <p>
          <span>性别：</span>
          <select
            name="sex"
            value={sex}
            onChange={this.handleChange.bind(this)}
          >
            <option value="meal">男</option>
            <option value="femeal">女</option>
          </select>
        </p>

        <p>
          <span>学生：</span>
          <input
            type="radio"
            name="isStudent"
            checked={isStudent}
            onChange={this.handleStuChange.bind(this, true)}
          />
          是|
          <input
            type="radio"
            name="isStudent"
            checked={!isStudent}
            onChange={this.handleStuChange.bind(this, false)}
          />
          否
        </p>

        <p>
          <span>hobbys：</span>
          {hobbiesData.map((item) => {
            return (
              <span key={item.value}>
                <span key={item.value}>{item.name}</span>
                <input
                  type="checkbox"
                  name="hobbies"
                  value={item.value}
                  checked={hobbies.includes(item.value)}
                  onChange={this.handleHobbiesChange.bind(this)}
                />
              </span>
            );
          })}
        </p>

        <p>
          <button onClick={this.submit.bind(this)}>submit</button>
          <button onClick={() => this.reset()}>reset</button>
        </p>
      </div>
    );
  }
}

ReactDOM.render(<App />, document.querySelector("#app"));

非受控组件

表单数据不受控于 state，使用 React ref 从 DOM 节点中获取表单数据的组件

class App extends React.Component {
  constructor(props) {
    super(props);
    // 推荐使用：React.createRef()
    this.usernameRef = React.createRef();
    this.pwdRef = React.createRef();
    this.genderRef = React.createRef();
    this.fileRef = React.createRef();
  }

  handleChange(e) {
    // refs 被弃用了
    // console.log(this.refs.usernameRef.value);

    this.setState({
      // [e.target.name]: this.refs.usernameRef.value,
      [e.target.name]: this.usernameRef,
    });
  }

  submit(e) {
    e.preventDefault();
    console.log(this.usernameRef.current.value);
    console.log(this.genderRef.current.value);
    console.log(this.fileRef.current.value);
  }
  reset(e) {
    e.preventDefault();
    this.usernameRef.current.value = "";
  }

  render() {
    return (
      <div>
        <p>
          <span>用户名：</span>
          <input
            type="text"
            name="username"
            ref={this.usernameRef}
            onChange={this.handleChange.bind(this)}
          />
        </p>

        <p>
          {/* 
            form field 默认值
            组件挂载完毕后更新，不会导致 DOM 的任何更新
          */}
          <select defaultValue="male" ref={this.genderRef}>
            <option value="male">男</option>
            <option value="female">女</option>
          </select>
        </p>

        <p>
          <input type="file" ref={this.fileRef} />
        </p>

        <p>
          <button onClick={this.submit.bind(this)}>submit</button>
          <button onClick={(e) => this.reset(e)}>reset</button>
        </p>
      </div>
    );
  }
}

ReactDOM.render(<App />, document.querySelector("#app"));