javascript - React Native - 如何在类组件中初始化对象？

Question

当我尝试在类组件中初始化一个对象时收到此错误消息。

错误信息

    Failed to load bundle(http://localhost:8081/index.bundle?platform=ios&dev=true&minify=false) with error:(SyntaxError: /blockchain/node_modules/react-native/App.js: Unexpected token (9:6)

我的代码

App.js

import Block from './block.js'

export default class App extends Component {

  let genesisBlock = new Block(); //error here
  let blockchain = new Blockchain(genesisBlock);

  render() {
    return (
      </View>

    );
  }
}

block .js

export default class Block {
    constructor() {
        this.index = 0
        this.previousHash = ""
        this.hash = ""
        this.nonce = 0
        this.transactions = []
     }

     addTransaction(transaction) {
        this.transactions.push(transaction)
    }

    get key() {
        return JSON.stringify(this.transactions) + this.index + this.previousHash + this.nonce
    }
}

但是如果我删除let，它会说找不到变量genesisBlock。

引用:https://github.com/datomnurdin/blockchain-reactnative

Answer 1

尝试:

import Block from './block.js'

export default class App extends Component {
  constructor(){
    super()
    this.genesisBlock = new Block();
    this.blockchain = new Blockchain(this.genesisBlock);
  }

  render() {
    return (
      <View/>
    );
  }
}