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React Native Web

· 12 min read
Havit Rovik

Comprehensive Guide to create simple app using React Native Web and React Native Elements

Case study: gitphone, GitHub repository checker for your smartphone.

ToC#

  • Initialize the project using CRNWA
  • Make sure everything works: Android, iOS and Web
  • Add RNE latest ( 1.0.0-beta7 ) to the project
  • Add 2 screens

Screen 1 RNE components:

  1. Input
  2. Button with Icon

Screen 2 RNE components:

  1. Header
  2. ListItem
  3. Avatar
  4. Text

gitphone should have:

0️⃣ Initial Step#

Install create-react-native-web-app

$ npm i -g create-react-native-web-app

1️⃣ First Step#

Create gitphone project.

λ create-react-native-web-app gitphone
⏳ Creating React Native Web App by the name of gitphone ...
✅ Created project folder.
✅ Added project files.
⏳ Installing project dependencies...
yarn install v1.10.1[1/4] Resolving packages...[2/4] Fetching packages...info fsevents@1.2.4: The platform "win32" is incompatible with this module.info "fsevents@1.2.4" is an optional dependency and failed compatibility check. Excluding it from installation.[3/4] Linking dependencies...[4/4] Building fresh packages...success Saved lockfile.Done in 797.66s.
✅ Installed project dependencies.
✅ Done! 😁👍 Your project is ready for development.
* change directory to your new project$ cd gitphone
$ Then run the these commands to get started:
* To run development Web server$ yarn web
* To run Android on connected device (after installing Android Debug Bridge "adb" - https://developer.android.com/studio/releases/platform-tools)$ yarn android
* To run ios simulator (after installing Xcode - only on Apple devices)$ yarn ios
* To run tests for Native and Web$ yarn test
* To run build for Web$ yarn build

Change to gitphone directory and test the web app by running yarn web.

Starting the development server...Compiled successfully!You can now view create-react-native-web-app in the browser.Local:            http://localhost:3001/On Your Network:  http://172.26.235.145:3001/Note that the development build is not optimized.To create a production build, use yarn build.

Now, test the gitphone android app by running yarn android.

Installing APK 'app-debug.apk' on 'Redmi 4X - 7.1.2' for app:debugInstalled on 1 device.
BUILD SUCCESSFUL
Total time: 21.783 secs
Starting: Intent { cmp=com.creaternwapp/.MainActivity }✨  Done in 25.64s.

If the build successful, you'll see the app installed on your Android (emulator) device.

But if you got an error when run yarn android, please see Troubleshooting section below.

The last part for First Step, make sure it can be run on iOS without any problem. Run yarn ios and voila!

2️⃣ Step Two#

Installing React Native Elements (RNE).

$ yarn add react-native-elements@beta

Installing React Native Vector Icons (RNVI).

$ yarn add react-native-vector-icons

Linking:

$ react-native link react-native-vector-icons

Both RNE and RNVI are written using es6. If you run yarn web at this point, you'll got an error.

./node_modules/react-native-elements/src/config/withTheme.jsModule parse failed: Unexpected token (12:28)You may need an appropriate loader to handle this file type.

We need to tell webpack to transpile them.

  1. Open config/webpack.config.dev.js
  2. On line 141 Process JS with babel, add RNE and RNVI to include
  3. Do the same for config/webpack.config.prod.js as well 👌

If you get lost, see this gist or commit 8c0e603.

3️⃣ Give it a try#

Now, let's grasp the idea how RNE works.

  1. Open src/App.js

  2. Import Button from RNE

    import { Button } from 'react-native-elements';

  3. On render, change TouchableHighlight to use RNE's Button

  4. Run yarn ios, yarn android and yarn web to see it in action! 👏

Note: If you got an error Could not find com.android.tools.build.appt2 when running yarn android, add google on the gradle repositories.

See this gist or commit for the details: a2ebba1.

4️⃣ Add Home component#

Our first component will be Home. On this component, there are two input fields and one Submit button.

  1. Inside src, create new folder: Components
  2. Add new file called Home.js gist
  3. On App.js, import Home component gist
  4. Run yarn ios, yarn android and yarn web to see it in action! 🎇

Styling for Home component#

You should notice that our Home doesn’t look good in term of UI. Let’s add styling for it.

  1. Inside Components, create Shared.style.js file gist
  2. Import the style and update Home component as below gist
  3. Looks better now*, commit for adding Home component: 2e510c4.

Wait a minute… *Seems there is a problem with RNVI on the web version. You can check this Web (with webpack) article or just following steps bellow.

  1. Open config/webpack.config.dev.js
  2. Add url-loader on line 162 gist
  3. Do the same for config/webpack.config.prod.js as well 👌
  4. Open src/index.js file
  5. Add iconFont and append style to document’s head gist

Our RNE x RNW progress so far~Our RNE x RNW progress so far~

5️⃣ Routing#

Next, let’s add second component: CommitList.

  1. Create new folder inside Components named Commit
  2. Add new file: CommitList.js gist

On our app, user goes to second screen by click on Submit button. How do we implement it?

“react-router comes to the rescue” - https://reacttraining.com/react-router/

Add react-router-dom and react-router-native

$ yarn add react-router-dom react-router-native

Web needs BrowserRouter while native NativeRouter. We need to separate it based on the platform.

  1. On src, create Utils folder
  2. Add two files on Utils: Routing.native.js and Routing.web.js gist

Those file’s content differ only on the second line. gist

Now, glue it together.

  1. Open App.js, import CommitList component

  2. Import Route, Router and Switch from Utils/Routing

  3. Implement routing inside render method gist

  4. Now for the action on Submit button, open Home.js

  5. Import withRouter from Utils/Routing

    import { withRouter } from '../Utils/Routing';

  6. WithRouter is an HOC. Use it to wrap Home component

    export default withRouter(Home);

  7. Add onPress property for the button

    onPress={this.onPressButton}

  8. Implement the onPressButton event handler

    onPressButton = () => this.props.history.push('/commit');

  9. All Home together gist | commit

Test it on web and android, you should be able to go back and forth between screens using Submit and pressing Back button.

“How can I go back on iOS?” 😂

Implement withHeader#

We will create a withHeader HOC. Why HOC? We can reuse it easier if we add more screens later.

  1. On src, create HOCs folder

  2. Add withHeader.js file

  3. Import Header from RNE and Icon from RNVI/FontAwesome

    import { Header } from 'react-native-elements';import Icon from 'react-native-vector-icons/FontAwesome';

  4. withHeader accepts one prop: title

    const withHeader = ({ title = '' }) => (WrappedComponent) => {

  5. Event handler to go back / go home

    goBack = () => this.props.history.goBack();
goHome = () => this.props.history.replace('/');

  6. Import and use withHeader in CommitList component gist | commit

6️⃣ Fetch data from GitHub API#

Let’s fetch a real-live data: list commit on repository by GitHub and render it on our second screen, CommitList.

GET /repos/:owner/:repo/commits

Ideally, the :owner and :repo are form values from our first screen. Since the objective of this article is RNE x RNW, talk about that form (and state-management) later on.

To fetch GitHub API, we will use fetch-hoc package and also need compose from redux, to handle multiple HOCs on the same component.

$ yarn add fetch-hoc redux

  1. Open CommitList.js

  2. Import { compose } from redux and fetch from fetch-hoc

  3. Use it as below gist | commit

Now run yarn web, open network tab of DevTools and click Submit button, you’ll see bunch of commit data. By default GitHub API returning 30 commits.

Render commit data#

Commit data that will be displayed on the screen:

author.avatar_url
commit:  author.name  message

Let’s modify CommitList.js

  1. Add new imports

    import { ActivityIndicator, Dimensions, FlatList, Platform, View } from 'react-native';import { Avatar, ListItem } from 'react-native-elements';

  2. On main render, modify it as below

    <View style={styles.container}>  {this.renderContent()}</View>

  3. Create renderContent method

    renderContent = () => (  this.props.loading ?    <ActivityIndicator color='#87ceeb' /> :    <FlatList      keyExtractor={this.keyExtractor}      data={this.props.data}      renderItem={this.renderItem}    />)

  4. Create renderItem method

    renderItem = ({ item }) => (  <ListItem    title={item.commit.author.name}    subtitle={item.commit.message}    leftElement={this.renderLeftElement(item)  />)

  5. Create renderLeftElement method

    renderLeftElement = (item) => (  <View>    <Avatar      source={{ uri: item.author.avatar_url }}      size='medium'      rounded    />  </View>)

  6. Here is our new CommitList including the styling to make it prettier gist | commit

Here they are!

awesome, eh?awesome, eh?

7️⃣ Handle form submission#

Our app looks great so far. But we are not passing values from first to second screen. Let’s do it.

  1. To handle form, we’ll use formik

    $ yarn add formik

  2. Open Home.js and import it

    import { Formik } from 'formik';

  3. Wrap main View with formik

    <Formik initialValues={{ owner: '', repo: '' }}  onSubmit={this.onPressButton}>  {({ handleChange, handleSubmit, values }) => (    <View style={styles.container}>

  4. Add onChangeText handler to the Input

    <Input ... onChangeText={handleChange('owner')} value={values.owner}<Input ... onChangeText={handleChange('repo')} value={values.repo}

  5. Change Button onPress props to handleSubmit

    <Button ... onPress={handleSubmit}

  6. Don’t forget to close the main View

        </View>  )}</Formik>

Form submission: done 👌 Next question: How do we pass these values to second screen? Send them when we redirect to second screen!

  1. Inside onPressButton method, send an object instead of pathname only.

    this.props.history.push({  pathname: '/commit',  state: { owner, repo }});

  2. Open CommitList, import withRouter

    import { withRouter } from '../../Utils/Routing';

  3. Add withRouter inside compose

  4. Get the values passed down to withRouter and use it to fetch

    withHeader({ title: 'Commits' }),withRouter,fetch(({ location: { state = {} } }) => ( `https://api.github.com/repos/${state.owner}/${state.repo}/commits`))

HOC’s order does matter. So, make sure it the same as snippet above. In case you lost, here is the commit: 1d83c5e.

Test the app. Now we should able to fetch any GitHub repository, with some caveats. 👀

8️⃣ Polishing the app#

What happens if we fetch repository which doesn’t exist? Red screen on native, blank screen on web! 😹

fetch-hoc returns an error if it has. Let’s use it.

  1. On CommitList, modify renderContent

    this.props.loading ?  <ActivityIndicator color='#87ceeb' /> :  this.renderFlatList()

  2. Import Text from RNE

    import { ..., Text } from 'react-native-elements';

  3. Add renderFlatList method

    this.props.error ?  <Text h4>Error: {this.props.data.message || '😕'}</Text> :  <FlatList ... />

Test it. Instead of red or blank screen, now Error: Not Found displayed.

What’s else? Try to fetch facebook/react-native. We got another error 🙀

Cannot read property 'avatar_url' of null

Not all of author have avatar_url. We should do this for the Avatar source.

source={{uri: (item.author && item.author.avatar_url) || undefined}}

So, our app renders nothing if it has no url? It doesn’t look good. Solution: render author initial name.

With the help of RegEx and Avatar title props, renderLeftElement should look like this now:

renderLeftElement = (item) => {  const initials = item.commit.author.name.match(/\b\w/g) || [];
return (    <View style={leftElementStyle}>      <Avatar        title={((initials.shift() || '') + (initials.pop() || ''))}        ...

Commit for Polishing the app section: 943974b.

When I wrote this, fetch facebook/react-native returning following:

Why no love for regex? Thanks to [Sanoor](https://stackoverflow.com/a/33076482).Why no love for regex? Thanks to Sanoor.

Conclusion#

We have created a simple app using RNE + RNW 👏

  • Works great on iOS, web and android? ✅

  • Use components from react-native-elements? ✅

  • Move between screens? ✅

  • API calls? ✅

Some improvements for gitphone:

If you go back from Commits screen, input form on Home screen are empty. If you want preserve previous values, this can be fixed easily by introducing redux to the app. References here: 48108dd.

Can we fetch more commits data once we reach the most bottom of the list? Infinite scroll?

For web, we can use react-visibility-sensor. Check it out: 6c1f689.

For native, it’s easier. We can use FlatList onEndReached props. To give you an idea how, see this: 9d2e1f2.

Troubleshooting 💺#

#1 Build failed when running yarn android

:app:compileDebugAidl FAILED
FAILURE: Build failed with an exception.
* What went wrong:Execution failed for task ':app:compileDebugAidl'.> java.lang.IllegalStateException: aidl is missing
* Try:Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.
BUILD FAILED

Here is how to fix #1:

  1. Open Android Studio.

  1. Open android project under gitphone.

  1. Click Update on this prompt.

Wait for Android Studio syncing the project.

  1. It synced successfully with two errors.

  1. At this stage, just click Update Build Tools version and sync project on the sync window.

  2. Now, the remaining warning is the Configuration 'compile'...

  3. To fix that, open app/build.gradle file, change dependencies section (line 139) to use implementation instead of compile.

    dependencies { implementation fileTree(dir: "libs", include: ["*.jar"]) implementation "com.android.support:appcompat-v7:23.0.1" implementation "com.facebook.react:react-native:+" }

  4. Sync it again and close Android Studio.

Troubleshooting for android is done. Now, you should be able to run yarn android successfully.

#2 Build failed when running yarn ios

** BUILD FAILED **
The following build commands failed:
 CompileC /gitphone/ios/build/Build/Intermediates.noindex/React.build/Debug-iphonesimulator/double-conversion.build/Objects-normal/x86_64/strtod.o /gitphone/node_modules/react-native/third-party/double-conversion-1.1.5/src/strtod.cc normal x86_64 c++ com.apple.compilers.llvm.clang.1_0.compiler

Here is how to fix #2:

Inside the project, run script below from your favourite terminal

$ curl -L https://git.io/fix-rn-xcode10 | bash

If you run yarn ios again, and you got this error

The following build commands failed: Libtool /gitphone/ios/build/Build/Products/Debug-iphonesimulator/libRCTWebSocket.a normal x86_64(1 failure)

Please run this script:

$ cp ios/build/Build/Products/Debug-iphonesimulator/libfishhook.a node_modules/react-native/Libraries/WebSocket

Troubleshooting for iOS is done. Now, you should be able to run yarn ios successfully.

Authors#