I'm trying to Use AppLoading to render home screen components but cant get the splash screen to stay until everything is loaded - react-hooks

After optimising my images iv realised that I still need more time for my components to load. They are card like components with images.
I have 2 components to load one is in a flatList, the other just a basic card like component each component contains images. I have been trying in vain to get this to work and have to ask if anyone has a good solution. Here's what I have so far.
import React, { useState } from "react";
import { View, StyleSheet } from "react-native";
import AppLoading from "expo-app-loading";
import Header from "./components/Header";
import HomeScreen from "./screens/HomeScreen";
const fetchHomeScreen = () => {
return HomeScreen.loadAsync({
HomeScreen: require("./screens/HomeScreen"),
Header: require("./components/Header"),
});
};
export default function App() {
const [HomeScreenLoaded, setHomeScreenLoaded] = useState(false);
if (!HomeScreenLoaded) {
return (
<AppLoading
startAsync={fetchHomeScreen}
onFinish={() => setHomeScreenLoaded(true)}
onError={(err) => console.log(err)}
/>
);
}
return (
<View style={styles.screen}>
<Header title="Your Beast Log" />
<HomeScreen />
</View>
);
}
const styles = StyleSheet.create({
screen: {
flex: 1,
backgroundColor: "#3E3636",
},
});

Are you using expo status bar ?? then try these;
import splash screen
import * as SplashScreen from 'expo-splash-screen';
add this to the top of main function
SplashScreen.preventAutoHideAsync()
export default function App() {....}
then add this to your screen where you hide the splash screen
const [appIsReady, setAppIsReady] = useState(false);
useEffect(() => {
if(appIsready) {
(async () => {
await SplashScreen.hideAsync();
})()
}
},[appIsReady])
async function prepare() {
try {
await fetchHomeScreen;
//OR
await HomeScreen.loadAsync({
HomeScreen: require("./screens/HomeScreen"),
Header: require("./components/Header"),
});
} catch (e) {
console.warn(e);
} finally {
// Tell the application to render
setAppIsReady(true);
}
}

Related

What should I expect for navigate buttons in react using react-testing library

I don't understand what should I expect for navigate button in the below code. can any one help me with this. Thank you.
code:
import react from 'react';
const HomeButton = (props) => {
const history = props.history;
function handleClick() {
history.push("/home");
}
return (
<button type="button" onClick={handleClick} data-testid="goToHome">
Go home
</button>
);
}
export default HomeButton;
This is the test code I have been trying for the above component
import React from 'react';
import { render, screen, fireEvent } from '#testing-library/react';
import GoToHome from '../GoToHome';
describe('Read only text', () => {
const history = createMemoryHistory();
it('text came from props', () => {
const { container } = render(<GoToHome history={history} />);
const goToHome = screen.getByTestId('goToHome')
fireEvent.click(goToHome, jest.fn())
expect(container).
});
});
you can check my passing the history as a prop with push property assigned to jest.fn as mock function and check if it is getting called when you press to navigate button
describe('Read only text', () => {
const mockPush = jest.fn()
const history = {
push: mockPush()
}
it('text came from props', () => {
const { container } = render(<GoToHome history={history} />);
const goToHome = screen.getByTestId('goToHome')
fireEvent.click(goToHome)
expect(mockPush ).toBeCalled()
});
});

How do I render an image using map function?

I've tried do render the image from URL but I have no success. If write the URI ok, but if I write item.show.image.original.replace ('http:', 'https:') to get the image no success.
The problem is thereĀ“s no error but not rendering.
The others values I've had success with.
import React, { Component } from "react";
import { Text, View, Image } from "react-native";
let termo = 'batman';
const API = 'http://api.tvmaze.com/search/shows?q='+termo;
export default class mapFunction extends Component {
constructor(props) {
super(props);
this.state = {
array: [], };
}
componentDidMount() {
fetch(API)
.then(response => response.json())
.then(data => this.setState({ array: data}));
}
list = () => {
return this.state.array.map(item => {
return (
<View style={{marginLeft: 10}}>
<Text>{item.score}</Text>
<Text>{item.show.name}</Text>
<Text>{item.show.type}</Text>
<Text>{item.show.language}</Text>
<Text>{item.show.summary} </Text>
<Image source={{uri:'https://static.tvmaze.com/uploads/images/original_untouched/6/16463.jpg'}}
style={{width:90, height:150}} />
</View>
);
});
};
render() {
return <View>{this.list()}
</View>;
}
}
Just change render function as below:
render() {
return (
<View>{this.list()}</View>
);
}

React.js using context api to implement the dark/light theme, is it possible to get data in App component when I am using contextprovider?

I am using the context api to give my application the toggling ability between the dark/light mode, I managed to toggle the mode in all the children components of App component but when I tried to implement it to the component itself I failed I guess this related the fact the I am using the contextProvider within this component, code below for :
import React from 'react'
import styles from './App.module.css'
import { Card, CountryPicker, Chart } from './components/index'
import { fetchData } from './api/index'
import ThemeContextProvider, { ThemeContext } from './contexts/ThemeContext'
import ToggleTheme from './components/ToggleTheme/ToggleTheme'
export default class App extends React.Component {
static contextType = ThemeContext
state = {
data: {},
country: '',
}
handleCountryChange = async (country) => {
// console.log(country)
const Data = await fetchData(country)
// console.log(Data)
this.setState({ data: Data, country })
// console.log(this.state.data, this.state.country)
}
async componentDidMount() {
const data = await fetchData();
this.setState({ data })
}
render() {
const { data, country } = this.state;
// problem here
const { isLightTheme, dark, light } = this.context;
return (
<ThemeContextProvider>
<div className={styles.container} >
<ToggleTheme />
<Card data={data} />
<CountryPicker handleCountryChange={this.handleCountryChange} />
<Chart data={data} country={country} />
</div>
</ThemeContextProvider>
)
}
}
I figured it out,the solution was very simple, just importing the App component into other componentMain and wrapping it with <ContextProvider></ContextProvider> and import in the index.js

react-navigation - Cannot read property 'navigate' of undefined

I'm new in React Native and trying create my first app. So I have a question:
I got 2 screens (using react-navigation). At first screen there is a render of app logo with spinner(from native-base) and fetch to the server at the same time. And I need to navigate to another screen only when fetch is over and responce is handled. Please help me find my mistakes!
index.ios.js
import React, { Component } from 'react';
import {
AppRegistry,
StyleSheet,
Text,
View,
TextInput,TouchableHighlight
} from 'react-native';
import { StackNavigator } from 'react-navigation';
import LoadingScreen from './src/screens/LoadingScreen.js';
import MainContainer from './src/screens/MainContainer.js';
export default class Calculator2 extends Component {
render() {
return (
<LoadingScreen/>
);
}
}
const AppNavigator = StackNavigator({
Loading: {
screen: LoadingScreen
},
Main: {
screen: MainContainer
}
});
AppRegistry.registerComponent('Calculator2', () => Calculator2);
LoadingScreen.js:
import React, { Component } from 'react';
import {
AsyncStorage,
AppRegistry,NetInfo,
Text,Image,View
} from 'react-native';
import { StackNavigator } from 'react-navigation';
import AppNavigator from '../../index.ios.js';
import { Container, Header, Content, Spinner } from 'native-base';
export default class LoadingScreen extends Component {
static navigationOptions = {
title: 'Loading',
};
constructor(props){
super(props);
}
componentDidMount(){
const {navigate} = this.props.navigation;
fetch('url').then( (response) => {navigate('Main')});
}
render() {
return(
<View>
App logo with spinner
</View>
);
}
}
MainContainer.js
import React, { Component } from 'react';
import {
AppRegistry,Alert,NetInfo,
StyleSheet,
Text,
View,ActivityIndicator,
TextInput,TouchableHighlight
} from 'react-native';
import { StackNavigator } from 'react-navigation';
import AppNavigator from '../../index.ios.js';
export default class MainContainer extends Component {
static navigationOptions = {
title: 'Main',
};
render() {
return (
<View style={{flexDirection: 'column'}}>
...
</View>
);
}
}
And all I got is an error "Cannot read property 'navigate' of undefined" at LoadingScreen.componentDidMount
UPD
actually my fetch should be a function getting responce and handling it, and it should wait till handling is done:
async function getData(){
var response = await fetch('url', {
method: 'GET'
});
storage = await response.json(); // storage for response
regions = Object.keys(storage); // an array of regions names
console.log(storage, Object.keys(storage));
};
You need to register AppNavigator component instead of Calculator2
AppRegistry.registerComponent('Calculator2', () => AppNavigator);
Just update your LoadingScreen.js's componentDidMount function as following:
componentDidMount() {
var self = this;
fetch('url').then( (response) => {
self.props.navigation.navigate('Main')
});
}

Scroll to the top of the page after render in react.js

I have a problem, which I have no ideas, how to solve.
In my react component I display a long list of data and few links at the bottom.
After clicking on any of this links I fill in the list with new collection of the links and need to scroll to the top.
The problem is - how to scroll to the top after new collection is rendered?
'use strict';
// url of this component is #/:checklistId/:sectionId
var React = require('react'),
Router = require('react-router'),
sectionStore = require('./../stores/checklist-section-store');
function updateStateFromProps() {
var self = this;
sectionStore.getChecklistSectionContent({
checklistId: this.getParams().checklistId,
sectionId: this.getParams().sectionId
}).then(function (section) {
self.setState({
section,
componentReady: true
});
});
this.setState({componentReady: false});
}
var Checklist = React.createClass({
mixins: [Router.State],
componentWillMount: function () {
updateStateFromProps.call(this);
},
componentWillReceiveProps(){
updateStateFromProps.call(this);
},
render: function () {
if (this.state.componentReady) {
return(
<section className='checklist-section'>
<header className='section-header'>{ this.state.section.name } </header>
<Steps steps={ this.state.section.steps }/>
<a href=`#/${this.getParams().checklistId}/${this.state.section.nextSection.Id}`>
Next Section
</a>
</section>
);
} else {...}
}
});
module.exports = Checklist;
Finally.. I used:
componentDidMount() {
window.scrollTo(0, 0)
}
EDIT: React v16.8+
useEffect(() => {
window.scrollTo(0, 0)
}, [])
Since the original solution was provided for very early version of react, here is an update:
constructor(props) {
super(props)
this.myRef = React.createRef() // Create a ref object
}
componentDidMount() {
this.myRef.current.scrollTo(0, 0);
}
render() {
return <div ref={this.myRef}></div>
} // attach the ref property to a dom element
You could use something like this. ReactDom is for react.14. Just React otherwise.
componentDidUpdate = () => { ReactDom.findDOMNode(this).scrollIntoView(); }
Update 5/11/2019 for React 16+
constructor(props) {
super(props)
this.childDiv = React.createRef()
}
componentDidMount = () => this.handleScroll()
componentDidUpdate = () => this.handleScroll()
handleScroll = () => {
const { index, selected } = this.props
if (index === selected) {
setTimeout(() => {
this.childDiv.current.scrollIntoView({ behavior: 'smooth' })
}, 500)
}
}
In React Routing there is the problem that if we redirect to the new route, then it won't automatically take you to the top of the page.
Even I did have the same issue.
I just added the single line to my component and it worked like butter.
componentDidMount() {
window.scrollTo(0, 0);
}
Refer: react training
Hook solution:
Create a ScrollToTop hook
import { useEffect } from "react";
import { withRouter } from "react-router-dom";
const ScrollToTop = ({ children, location: { pathname } }) => {
useEffect(() => {
window.scrollTo({
top: 0,
left: 0,
behavior: "smooth"
});
}, [pathname]);
return children || null;
};
export default withRouter(ScrollToTop);
Wrap your App with it
<Router>
<ScrollToTop>
<App />
</ScrollToTop>
</Router>
Documentation : https://reacttraining.com/react-router/web/guides/scroll-restoration
For those using hooks, the following code will work.
React.useEffect(() => {
window.scrollTo(0, 0);
}, []);
Note, you can also import useEffect directly: import { useEffect } from 'react'
This could, and probably should, be handled using refs:
"... you can use ReactDOM.findDOMNode as an "escape hatch" but we don't recommend it since it breaks encapsulation and in almost every case there's a clearer way to structure your code within the React model."
Example code:
class MyComponent extends React.Component {
componentDidMount() {
this._div.scrollTop = 0
}
render() {
return <div ref={(ref) => this._div = ref} />
}
}
You can do this in the router like that:
ReactDOM.render((
<Router onUpdate={() => window.scrollTo(0, 0)} history={browserHistory}>
<Route path='/' component={App}>
<IndexRoute component={Home}></IndexRoute>
<Route path="/about" component={About}/>
<Route path="/work">
<IndexRoute component={Work}></IndexRoute>
<Route path=":id" component={ProjectFull}></Route>
</Route>
<Route path="/blog" component={Blog}/>
</Route>
</Router>
), document.getElementById('root'));
The onUpdate={() => window.scrollTo(0, 0)} put the scroll top.
For more information check: codepen link
This works for me.
import React, { useEffect } from 'react';
useEffect(() => {
const body = document.querySelector('#root');
body.scrollIntoView({
behavior: 'smooth'
}, 500)
}, []);
Here's yet another approach that allows you to choose which mounted components you want the window scroll position to reset to without mass duplicating the ComponentDidUpdate/ComponentDidMount.
The example below is wrapping the Blog component with ScrollIntoView(), so that if the route changes when the Blog component is mounted, then the HOC's ComponentDidUpdate will update the window scroll position.
You can just as easily wrap it over the entire app, so that on any route change, it'll trigger a window reset.
ScrollIntoView.js
import React, { Component } from 'react';
import { withRouter } from 'react-router';
export default WrappedComponent => {
class ResetWindowScroll extends Component {
componentDidUpdate = (prevProps) => {
if(this.props.location !== prevProps.location) window.scrollTo(0,0);
}
render = () => <WrappedComponent {...this.props} />
}
return withRouter(ResetWindowScroll);
}
Routes.js
import React from 'react';
import { Route, IndexRoute } from 'react-router';
import App from '../components/App';
import About from '../components/pages/About';
import Blog from '../components/pages/Blog'
import Index from '../components/Landing';
import NotFound from '../components/navigation/NotFound';
import ScrollIntoView from '../components/navigation/ScrollIntoView';
export default (
<Route path="/" component={App}>
<IndexRoute component={Index} />
<Route path="/about" component={About} />
<Route path="/blog" component={ScrollIntoView(Blog)} />
<Route path="*" component={NotFound} />
</Route>
);
The above example works great, but if you've migrated to react-router-dom, then you can simplify the above by creating a HOC that wraps the component.
Once again, you could also just as easily wrap it over your routes (just change componentDidMount method to the componentDidUpdate method example code written above, as well as wrapping ScrollIntoView with withRouter).
containers/ScrollIntoView.js
import { PureComponent, Fragment } from "react";
class ScrollIntoView extends PureComponent {
componentDidMount = () => window.scrollTo(0, 0);
render = () => this.props.children
}
export default ScrollIntoView;
components/Home.js
import React from "react";
import ScrollIntoView from "../containers/ScrollIntoView";
export default () => (
<ScrollIntoView>
<div className="container">
<p>
Sample Text
</p>
</div>
</ScrollIntoView>
);
This solution is working for the Functional component as well as the Class Base.
First of all, I do not like the idea of Scroll to top on every re-render, instead, I like of attache function to the particular event.
Step #1: Create a function to ScrollToTop
const scrollToTop = () => {
window.scrollTo({
top: 0,
behavior: "smooth",
});
};
Step #2: Call this function on an event e.g onClick
onRowClick={scrollToTop()}
// onClick={scrollToTop()}
// etc...
I'm using react-router ScrollToTop Component which code described in react-router docs
https://reacttraining.com/react-router/web/guides/scroll-restoration/scroll-to-top
I'm changing code in single Routes file and after that no need of change code in every component.
Example Code -
Step 1 - create ScrollToTop.js Component
import React, { Component } from 'react';
import { withRouter } from 'react-router';
class ScrollToTop extends Component {
componentDidUpdate(prevProps) {
if (this.props.location !== prevProps.location) {
window.scrollTo(0, 0)
}
}
render() {
return this.props.children
}
}
export default withRouter(ScrollToTop)
Step 2 - In App.js file, add ScrollToTop Component after <Router
const App = () => (
<Router>
<ScrollToTop>
<App/>
</ScrollToTop>
</Router>
)
If all want to do is something simple here is a solution that will work for everybody
add this mini function
scrollTop()
{
window.scrollTo({
top: 0,
behavior: "smooth"
});
}
call the function as following from the footer of the page
<a className="scroll-to-top rounded" style={{display: "inline"}} onClick={this.scrollTop}>TOP</a>
if you want to add nice styles here is the css
.scroll-to-top {
position: fixed;
right: 1rem;
bottom: 1rem;
display: none;
width: 2.75rem;
height: 2.75rem;
text-align: center;
color: #fff;
background: rgba(90, 92, 105, 0.5);
line-height: 46px;
}
This is the only thing that worked for me (with an ES6 class component):
componentDidMount() {
ReactDOM.findDOMNode(this).scrollIntoView();
}
All of the above didn't work for me - not sure why but:
componentDidMount(){
document.getElementById('HEADER').scrollIntoView();
}
worked, where HEADER is the id of my header element
I have tried #sledgeweight solution but it does not work well for some of the views. But adding a setTimeout seems to work perfectly. In case someone facing the same issue as me. Below is my code.
import { useEffect } from 'react'
import { useLocation } from 'react-router-dom'
const ScrollToTop = () => {
const { pathname } = useLocation()
useEffect(() => {
console.log(pathname)
/* settimeout make sure this run after components have rendered. This will help fixing bug for some views where scroll to top not working perfectly */
setTimeout(() => {
window.scrollTo({ top: 0, behavior: 'smooth' })
}, 0)
}, [pathname])
return null
}
export default ScrollToTop
Use it in AppRouter.js as
<Router>
<ScrollToTop/>
<App>
</Router>
Using Hooks in functional components,
assuming the component updates when theres an update in the result props
import React, { useEffect } from 'react';
export const scrollTop = ({result}) => {
useEffect(() => {
window.scrollTo(0, 0);
}, [result])
}
The page that appears after clicking, just write into it.
componentDidMount() {
window.scrollTo(0, 0);
}
Smooth scroll to top . In hooks you can use this method inside lifecycle mounting state for once render
useEffect(() => {
window.scrollTo({top: 0, left: 0, behavior: 'smooth' });
}, [])
Looks like all the useEffect examples dont factor in you might want to trigger this with a state change.
const [aStateVariable, setAStateVariable] = useState(false);
const handleClick = () => {
setAStateVariable(true);
}
useEffect(() => {
if(aStateVariable === true) {
window.scrollTo(0, 0)
}
}, [aStateVariable])
I tried everything, but this is the only thing that worked.
useLayoutEffect(() => {
document.getElementById("someID").scrollTo(0, 0);
});
This is what I did:
useEffect(() => ref.current.scrollTo(0, 0));
const ref = useRef()
return(
<div ref={ref}>
...
</div>
)
I was doing a SPA in React 17.0 using functional components and window.scroll, window.scrollTo and all of this variants doesn't work for me. So I made a solution using useRef hook. I created a span tag in the top of the component with Ref and then I used and effect with ref.current.scrollIntoView()
There is a short example:
import React, { useEffect,useRef} from 'react';
export const ExampleComponent = () => {
const ref = useRef();
useEffect(() => {
ref.current.scrollIntoView()
}, []);
return(
<>
<span ref={ref}></span>
<YourCodeHere />
<MoreCode />
</>
)
}
For React v18+ my recommendation will be to use wrapper component, will be the easiest way to execute.
Step 1: Create a ScrollToTop component (component/ScrollToTop.js)
import { useEffect } from "react";
import { useLocation } from "react-router-dom";
export function ScrollToTop() {
const { pathname } = useLocation();
useEffect(() => {
window.scrollTo(0, 0);
}, [pathname]);
return null;
}
Step 2: Wrap your App with it (index.js)
<React.StrictMode>
<BrowserRouter>
<ScrollToTop />
<App />
</BrowserRouter>
</React.StrictMode>
Explanation: Every time pathname changes useEffect will be called to scroll the page to the top.
I'm using React Hooks and wanted something re-usable but also something I could call at any time (rather than just after render).
// utils.js
export const useScrollToTop = (initialScrollState = false) => {
const [scrollToTop, setScrollToTop] = useState(initialScrollState);
useEffect(() => {
if (scrollToTop) {
setScrollToTop(false);
try {
window.scroll({
top: 0,
left: 0,
behavior: 'smooth',
});
} catch (error) {
window.scrollTo(0, 0);
}
}
}, [scrollToTop, setScrollToTop]);
return setScrollToTop;
};
Then to use the hook you can do:
import { useScrollToTop } from 'utils';
const MyPage = (props) => {
// initialise useScrollToTop with true in order to scroll on page load
const setScrollToTop = useScrollToTop(true);
...
return <div onClick={() => setScrollToTop(true)}>click me to scroll to top</div>
}
I ran into this issue building a site with Gatsby whose Link is built on top of Reach Router. It seems odd that this is a modification that has to be made rather than the default behaviour.
Anyway, I tried many of the solutions above and the only one that actually worked for me was:
document.getElementById("WhateverIdYouWantToScrollTo").scrollIntoView()
I put this in a useEffect but you could just as easily put it in componentDidMount or trigger it any other way you wanted to.
Not sure why window.scrollTo(0, 0) wouldn't work for me (and others).
I had the same for problem for a while. Adding window.scrollTo(0, 0);to every page is painful and redundant. So i added a HOC which will wrap all my routes and it will stay inside BrowserRouter component:
<ScrollTop>
<Routes />
</ScrollTop>
Inside ScrollTopComponent we have the following:
import React, { useEffect } from "react";
import { useLocation } from "react-router-dom";
const ScrollTop = (props) => {
const { children } = props;
const location = useLocation();
useEffect(() => {
window.scrollTo(0, 0);
}, [location]);
return <main>{children}</main>;
};
export default ScrollTop;
Solution for functional component - Using useEffect() hook
useEffect(() => {
window.history.scrollRestoration = 'manual';}, []);
If you are doing this for mobile, at least with chrome, you will see a white bar at the bottom.
This happens when the URL bar disappears. Solution:
Change the css for height/min-height: 100% to height/min-height: 100vh.
Google Developer Docs
None of the above answers is currently working for me. It turns out that .scrollTo is not as widely compatible as .scrollIntoView.
In our App.js, in componentWillMount() we added
this.props.history.listen((location, action) => {
setTimeout(() => { document.getElementById('root').scrollIntoView({ behavior: "smooth" }) }, 777)
})
This is the only solution that is working universally for us. root is the ID of our App. The "smooth" behavior doesn't work on every browser / device. The 777 timeout is a bit conservative, but we load a lot of data on every page, so through testing this was necessary. A shorter 237 might work for most applications.

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