Accessing method of another component on React-Native

Question

I have 2 components A and B as below,

class A extends Component {

  testMethodA() {

  }

  render() {
      return (
          <View style={[styles.scene, {backgroundColor: 'red'}]}>
              <TouchableHighlight onPress={this.onPress}>
                  <Text>Welcome. Press here!</Text>
              </TouchableHighlight>
          </View>
      );
  }
}


class B extends Component {

  testMethodB() {

  }

  render() {
      return (
          <View style={[styles.scene, {backgroundColor: 'red'}]}>
              <TouchableHighlight onPress={this.onPress}>
                  <Text>Welcome. Press here!</Text>
              </TouchableHighlight>
          </View>
      );
  }
}

How can I access testMethodA from B and testMethodB from A?

Answer 1

There are two ways to get access to another component methods:

child accesses a parent method - props

class Child extends Component {
     render() {
         return (<div>{this.props.formatMessage(10)}</div>)
     }
}

class Parent extends Component {
     formatMessage(number) {
         return '$' + number;
     }
     render() {
         return (<Child formatMessage={this.formatMessage} />);
     }
}

parent accesses a child method - refs

class Child extends Component {
     getInnerData() {
          return 'some inner data'; 
     }
     render() {
         return (<div>child component</div>)
     }
}

class Parent extends Component {
     componentDidMount() {
         const childData = this.refs.child.getInnerData();
     }
     render() {
         return (<Child ref='child' />);
     }
}

What you should do is have a common parent that will hold the data of componentA & componentB and pass it between them as needed.

class Child1 extends Component {
     componentDidMount() {
         this.props.onMount('child 1');
     }
     render() {
         return (<div>I'm child1. child2 data is: {this.props.data}</div>)
     }
}

class Child2 extends Component {
     componentDidMount() {
         this.props.onMount('child 2');
     }
     render() {
         return (<div>I'm child2. child1 data is: {this.props.data}</div>)
     }
}

class Parent extends Component {

     render() {
         return (
             <div>
                  <Child1 onMount={(msg => this.setState(child1: msg)} data={this.state.child2} />
                  <Child2 onMount={(msg => this.setState(child2: msg)} data={this.state.child1} />
             </div>
         );
     }
}  

You can also combine the first & second methods (props & refs) to get the methods of componentA & componentB and pass them as props to you componentB & componentA respectively, but this is really not recommended