RN 入門之-元件建立的最新正確姿勢(⊙o⊙)

第一步初始化一個RN （這裡略過自行百度）
- [ ] 1. - > 專案根目錄先建立一個如

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */
import React, { Component } from 'react';
import {
  Platform,
  StyleSheet,
  Text,
  View
} from 'react-native';
//3種建立元件的方法
//1.使用ES6 建立元件
// export default class Hellocommpents extends Component<{}> {
 

//   render() {
//     return (
//       <Text style={{fontSize:15,backgroundColor:'green' }}> Hellocommpents</Text>
//     );
//   }
// }
//2.使用ES5 方式建立元件 次方法最新版本已經廢棄會報錯
// var Hellocommpents=React.createClass({
//   render(){
//     return
//       <Text style={{fontSize:15,backgroundColor:'green' }}> Hellocommpents</Text>
 

//
//   }
// } )
// module.exports=Hellocommpents;
//3 函式方式定義元件
function Hellocommpents() {
  //注意不帶；必死無疑O(∩_∩)O哈哈~
      return  <Text style={{fontSize:15,backgroundColor:'green' }}> Hellocommpents</Text>;
}
module.exports=Hellocommpents;
App.js中呼叫

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 

 */
import React, { Component } from 'react';
import {
  Platform,
  StyleSheet,
  Text,
  View
} from 'react-native';
import Hellocommpents from './Hellocommpents';
const instructions = Platform.select({
  ios: 'Press Cmd+R to reload,\n' +
    'Cmd+D or shake for dev menu',
  android: 'Double tap R on your keyboard to reload,\n' +
    'Shake or press menu button for dev menu',
});
export default class App extends Component<{}> {
  render() {
    return (
      <View style={styles.container}>
        <Hellocommpents/>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  },
  instructions: {
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,
  },
});