同样，这个也可以用。

handleChange: function(state,e) {
  this.setState({[state]: e.target.value});
},
render : function() {
  return (
    <form>
      <input type="text" name="email" placeholder="Email" value={this.state.email} onChange={this.handleChange.bind(this, 'email')} />
      <input type="password" name="password" placeholder="Password" value={this.state.password} onChange={this.handleChange.bind(this, 'password')}/>
      <button type="button" onClick={this.handleLogin}>Login</button>
    </form>
  );
},
handleLogin: function() {
  console.log("EMail: ", this.state.email);
  console.log("Password: ", this.state.password);
}

同样，这个也可以用。

handleChange: function(state,e) {
  this.setState({[state]: e.target.value});
},
render : function() {
  return (
    <form>
      <input type="text" name="email" placeholder="Email" value={this.state.email} onChange={this.handleChange.bind(this, 'email')} />
      <input type="password" name="password" placeholder="Password" value={this.state.password} onChange={this.handleChange.bind(this, 'password')}/>
      <button type="button" onClick={this.handleLogin}>Login</button>
    </form>
  );
},
handleLogin: function() {
  console.log("EMail: ", this.state.email);
  console.log("Password: ", this.state.password);
}

使用输入中的change事件来更新组件的状态，并在handllogin中访问它:

handleEmailChange: function(e) {
   this.setState({email: e.target.value});
},
handlePasswordChange: function(e) {
   this.setState({password: e.target.value});
},
render : function() {
      return (
        <form>
          <input type="text" name="email" placeholder="Email" value={this.state.email} onChange={this.handleEmailChange} />
          <input type="password" name="password" placeholder="Password" value={this.state.password} onChange={this.handlePasswordChange}/>
          <button type="button" onClick={this.handleLogin}>Login</button>
        </form>);
},
handleLogin: function() {
    console.log("EMail: " + this.state.email);
    console.log("Password: " + this.state.password);
}

工作小提琴。

此外，阅读文档，有一个完整的部分专门用于表单处理:表单

以前你也可以使用React的双向数据绑定助手mixin来实现同样的事情，但现在它被弃用了，取而代之的是设置值和更改处理程序(如上所述):

var ExampleForm = React.createClass({
  mixins: [React.addons.LinkedStateMixin],
  getInitialState: function() {
    return {email: '', password: ''};
  },
  handleLogin: function() {
    console.log("EMail: " + this.state.email);
    console.log("Password: " + this.state.password);
  },
  render: function() {
    return (
      <form>
        <input type="text" valueLink={this.linkState('email')} />
        <input type="password" valueLink={this.linkState('password')} />
        <button type="button" onClick={this.handleLogin}>Login</button>
      </form>
    );
  }
});

文档在这里:双向绑定助手。

有几种方法可以做到这一点:

1)通过索引从数组的表单元素中获取值

handleSubmit = (event) => {
  event.preventDefault();
  console.log(event.target[0].value)
}

2)在html中使用name属性

handleSubmit = (event) => {
  event.preventDefault();
  console.log(event.target.elements.username.value) // from elements property
  console.log(event.target.username.value)          // or directly
}

<input type="text" name="username"/>

3)使用裁判

handleSubmit = (event) => {
  console.log(this.inputNode.value)
}

<input type="text" name="username" ref={node => (this.inputNode = node)}/>

完整的示例

class NameForm extends React.Component {
  handleSubmit = (event) => {
    event.preventDefault()
    console.log(event.target[0].value)
    console.log(event.target.elements.username.value)
    console.log(event.target.username.value)
    console.log(this.inputNode.value)
  }
  render() {
    return (
      <form onSubmit={this.handleSubmit}>
        <label>
          Name:
          <input
            type="text"
            name="username"
            ref={node => (this.inputNode = node)}
          />
        </label>
        <button type="submit">Submit</button>
      </form>
    )
  }
}

如果你在项目中使用Redux，你可以考虑使用这个更高阶的组件https://github.com/erikras/redux-form。

你可以将按钮上的onClick事件处理程序切换到表单上的onSubmit处理程序:

render : function() {
      return (
        <form onSubmit={this.handleLogin}>
          <input type="text" name="email" placeholder="Email" />
          <input type="password" name="password" placeholder="Password" />
          <button type="submit">Login</button>
        </form>
      );
    },

然后，您可以使用FormData来解析表单(如果需要的话，还可以从其条目构造一个JSON对象)。

handleLogin: function(e) {
   const formData = new FormData(e.target)
   const user = {}

   e.preventDefault()

   for (let entry of formData.entries()) {
       user[entry[0]] = entry[1]
   }

   // Do what you will with the user object here
}