React-native reload app blank screen with this.state.array.map

React-native reload app blank screen with this.state.array.map

export default class App extends React.Component {
  constructor() {
    super();
    this.itemRef = firebaseApp.database().ref();
    this.state = {
      myArray: [],
    };
  }

  componentDidMount() {
    //get database from firebase
    //................
    this.setState({
      // load database into myArray
      // Example:
      //myArray: myDatabaseFirebase
    })
  }

  render() {
    return (
      <ViewPager>
        {this.state.myArray.map(item => {
          return (
            <Text>Something from database </Text>
          )
        })}
      </ViewPager>
    );
  }
}

when I run app it show blank screen, I think myArray did not load database so it null and the app show blank screen. How do I solve this problem ?


You need to learn JS and understand Sync/Async. You are updating your array outside of your listener callback. You should setState inside of callback.

Blank white screen on Android, IOS working fine! � Issue #2687 � wix , Issue Description I get a blank white screen on react-native No need to add RnnPackage and MainReactPackage return Arrays. local image asset for the tab icon selected state (optional, iOS only) Even this one file app white-screens on Android, runs fine on iOS. Reload to refresh your session. In my case, before loading the initialroute, the app shows blank screen for 2 or 3 seconds. The initial component loading takes time i think. Can someone tell me, what should i do to remove the blank screen.


On the first render, UI gets loaded and due to the async nature of your firebase data it takes time to get load hence you need to check whether the data is available or not in myArray. Since you have defined myArray as empty initially So we can directly check the length. just add condition

return (
  <ViewPager>
    {this.state.myArray.length > 0 && this.state.myArray.map(item => {
      return (
        <Text>Something from database </Text>
      )          
    })}
  </ViewPager>
);

react-native-community/react-native-viewpager, Currently, I have ViewPager setup with array of 4 items. just blank screen (with other bugs like showing deleted screen again) class App extends Component { state = { result: ['screen 1', 'screen 2', {this.state.result.map((item, index) => { return ( <View style={styles. Reload to refresh your session. Then, if I try to run react-native start and then press Reload on the app, the Metro server will detect the request, will build it and, upon reaching 100%, will render a white screen on the app. After this, closing the app, restarting the metro bundler, starting the app again is completely ineffective.


In the render method check if my array is not null and not empty

return (
  <ViewPager>
    {(this.state.myArray&&this.state.myArray.length>0)?
this.state.myArray.map(item => {
      return (
        <Text>Something from database </Text>
      )          
    })
:<Text>No data present</Text>
}
  </ViewPager>
);

Fast Refresh � React Native, Fast Refresh is a React Native feature that allows you to get near-instant feedback boundary can prevent you from always getting kicked out to the root app screen. Fast Refresh tries to preserve local React state in the component you're with an empty array of dependencies would still re-run once during Fast Refresh. 0 React-native run and reload app show blank screen Nov 28 '19 0 React-native reload app blank screen with this.state.array.map Nov 29 '19 0 Get data from Firebase to List is null (Flutter) Dec 6 '19


white screen react and refresh Code Example, Get code examples like "white screen react and refresh" instantly right from your google search results state: any; dispatch: React. This is likely because you' re using an outdated version of create-react-app. outside localhost � access css and js files inside resources folder in laravel � access index of array javascript� Hello all, I'm trying to make a simple app with a google maps, but I've a blank maps. My api_key is set, and I can see the requests on console API. this is my javascript file: import React, { Component } from 'react'; import { StyleSheet


Watch Out for Undefined State, Is your React component not rendering? Beware Undefined State Original render() { return ( <ul> {this.state.items.map(item => <li key={item.id}>{item.name} </li> )} </ul> ); } } This line says “extract the items key from this.props , and if it's undefined, set it to an empty array”. Get something on screen. In React, there are two ways to refresh a page: updating the state and forcing a page reload. Let’s explore both methods of using React to refresh a page. Method 1: Refresh a Page Using JavaScript. The first way of refreshing a page or component is to use vanilla JavaScript to call the reload method to tell the browser to reload the current page:


How To Delete An Item From An Array In React – Vegibit, The number of items in the array determines how many item components are One thing to keep in mind is what the difference is between props and state. let classes = "card-header h4 text-white bg-"; {this.state.items.map(item => ( jQuery Autocomplete As You Type � Todo App With Django And Bulma � Cisco Cloud� white screen on android. The whole day today I spent trying to build my app on android. But all the builds were successful only blank white screen show up at the end as a result. I tried to run the example project in this repo, again the same white screen. I am not sure what is going on or what I am doing wrong.