Get name of button onPress in react native

问题

I have two buttons that both call the same onPress function. In the callback I want to be able to differentiate between which was pressed.

<MKRadioButton
   title='A' 
   group={this.radioGroup}
   onPress={this._toggle}
 />

<MKRadioButton
   title='B' 
   group={this.radioGroup}
   onPress={this._toggle}
 />

then the call

_toggle(event) {
    //what should go here to figure out if title A or B was called?
}

回答1:

One solution is to pass that info as a parameter:

<MKRadioButton
  title='A' 
  group={this.radioGroup}
  onPress={(event) => this._toggle(event, 'A')}
/>

The callback would then use that parameter

_toggle(event, buttonId) {
  // Use buttonId
}

EDIT: Another solution is a parent component that always returns the title prop:

class RadioParent extends Component {
  render() {
    return (
      <MKRadioButton
        title={this.props.title} 
        group={this.props.radioGroup}
        onPress={(event) => this.props.onPress(event, this.props.title)}
      />
    );
  }
}

回答2:

To improve performance, you can bind the event handler in the constructor to have it rendered only once

Facebook tip (at the bottom of the page)

We generally recommend binding in the constructor or using the property initializer syntax, to avoid this sort of performance problem.

class MKRadioButtonWrapper extends React.PureComponent {
  constructor(props) {
    super(props);
    this.buttonPressed = this.buttonPressed.bind(this);
  }

  buttonPressed(){
    this.props.onPress(this.props.title);
  }

  render() {
    return (
    <MKRadioButton
       title={this.props.title}
       group={this.props.group}
       onPress={buttonPressed}
     />
    );
  }
}

class App extends React.Component {
  constructor(props) {
    super(props);

    this._toggle = this._toggle.bind(this);
  }

  _toggle(title) {
    //do what you want with the title
  }

  render() {
    return (
      <View>
        <MKRadioButtonWrapper
           title='A' 
           group={this.radioGroup}
           onPress={this._toggle}
         />

        <MKRadioButtonWrapper
           title='B' 
           group={this.radioGroup}
           onPress={this._toggle}
         />
      </View>
    );
  }
}

来源：https://stackoverflow.com/questions/44423132/get-name-of-button-onpress-in-react-native

标签

button

react-native

onpress