构建Javascript包过多，屏幕来回翻转

Question

很显然，我是React Native的新手。我正在使用世博会。我创建了该项目，添加了一个初始屏幕（顺便说一句，看起来不错），并且向App.js中添加了一些代码来登录用户。问题是：它不会退出构建。我不知道它叫什么，但是当我在命令行（Windows）中对项目进行“ expo start”时，它按预期方式打开了选项卡，并提供了QR码。但是当前的版本号是950（并且还在不断增加），而我已经工作了45分钟。在我的iPhone上，该应用在构建时会在初始屏幕和App.js（登录屏幕）之间切换。在项目目录中，唯一的其他.js文件是Home.js和一个旧文件AppOLD.js，该文件未在任何地方引用。在/ screens中，仅存在默认文件。谢谢您能给我的帮助！

App.js

import React, { Component } from 'react'
import { View, Text,  Alert, Button, TextInput, TouchableOpacity } from 'react-native';
import Home from './Home';
export default class App extends Component{
  state = {
    email: '',
    pwd: '',
    auth_token: '',
    userID: ''
  }
  Signup = async () => {
    fetch('https://myxyzwebsite.com/webuser_register', {
      method: 'post',
      headers: {
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        "provider": "email",
        "data": {
        "email": this.state.email,
        "pwd": this.state.pwd
        }
        })
    }).then((response) => response.json())
    .then((res) => {
      if(typeof(res.message) != "undefined"){
      Alert.alert("Error signing up", "Error: "+ res.message);
}
      else{
      this.setState({ auth_token: res.auth_token });
      Alert.alert("Success", "You have succesfully signed up");
      }
    }).catch((error) => {
       console.error(error);
    });
  }
  Login = async () => {
      var request = new XMLHttpRequest();
      var params = "email=" + this.state.email + "&pwd=" + this.state.pwd;
      request.onreadystatechange = (e) => {
    if (request.readyState !== 4) {
        return;
    }

  if (request.status === 200) {
    console.log('success', request.responseText);
    Alert.alert(request.responseText);
    if(request.responseText != "ERROR"){
       this.setState({ userID: request.responseText });
       Alert.alert("Welcome", " You have succesfully logged in");
    }else{
        Alert.alert("Oh, no!", " There was a problem");
    }
  } else {
    console.warn('error');
  }
};

request.open('POST', 'https://myxyzsite.com/wLoginCE');
request.send(params);

  }
  render(){
  //If auth token is not present
   if(this.state.userID==''){
     return(
     <View style={{
        flex: 1,
        flexDirection: 'column',
        justifyContent: 'center',
        alignItems: 'stretch',
      }}>
     <TextInput
           placeholder="Enter User name"
           onChangeText={ TextInputValue =>
           this.setState({email : TextInputValue }) }
           underlineColorAndroid='transparent'
           style={
           {
               textAlign: 'center',
               width: '90%',
               marginBottom: 7,
               height: 40,
               borderRadius: 5 ,
               fontSize: 20,
           }
         }
         />
     <TextInput
           placeholder="Enter password"
           onChangeText={ TextInputValue =>
           this.setState({pwd: TextInputValue }) }
           underlineColorAndroid='transparent'
           secureTextEntry={true}
           style={
           {
               textAlign: 'center',
               width: '90%',
               marginBottom: 7,
               height: 40,
               borderRadius: 5 ,
               fontSize: 20,
           }
         }
         />
        <TouchableOpacity onPress={this.Login.bind(this)}>
        <View style={{height: 50, backgroundColor:
        '#cc0066',justifyContent: 'center',
        alignItems: 'center',}}>
          <Text style={{
          fontSize: 20,
          color: '#FFFFFF',
          }}> 
          Login </Text>
        </View>
        </TouchableOpacity>
        <TouchableOpacity onPress={this.Signup.bind(this)}>
        <View style={{height: 50, backgroundColor:
        '#5da423',justifyContent: 'center',
        alignItems: 'center',}}>
          <Text style={{
          fontSize: 20,
          color: '#FFFFFF',
          }}> 
          Signup</Text>
        </View>
        </TouchableOpacity>

     </View>
        );
      }
/* Checking if the auth token is not empty directly sending the user to Home screen */
      else{
        return(
          <Home />
        );
    }
}
}

每个instructions

的Home.js为空。