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React Native is a great framework to implement your app for both Android and iOS platforms. But while it'southward widely supported by the React community and Facebook, it's notwithstanding far from version i.0.

Some of the errors you may encounter could exist misleading or very hard to find. Recently, the React Native team asked developers to help them determine which of these abrasive errors lead to the most frustration. While they did address some of the worst errors, in that location is still a handful remaining that could go under the radar.

Permit'southward expect at a few of these bug and discuss how to address them if they pop upward while you're developing your adjacent React Native app.

Import mistake

Invariant Violation: Chemical element type is invalid: expected a string (for born components) or a course/part (for blended components) but got: undefined. You likely forgot to export your component from the file information technology'due south defined in, or you might have mixed up default and named imports.

Bank check the render method of 'App'.

This error is located at:

in RCTScrollContentView (at ScrollView.js:1038)
in RCTScrollView (at ScrollView.js:1178)
in ScrollView (at App.js:25)
in RCTSafeAreaView (at SafeAreaView.js:55)
in SafeAreaView (at App.js:24)
in App (at renderApplication.js:40)
in RCTView (at AppContainer.js:101)
in RCTView (at AppContainer.js:119)
in AppContainer (at renderApplication.js:39)

The React Native squad has made this error more descriptive since the last version. Normally, mixed-up default and named imports are the culprits.

It's even so tricky because, as you can run into, the error is caused by a component that is imported into the app, simply we can't tell which ane is imported improperly. The prompt does non identify the component or even the line on which the fault appears.

To avoid this mistake when creating and exporting components, remember not to mix default and named imports. What'due south the divergence?

Let's say your component has the post-obit.

export const componentName        

You'd have to import information technology like this:

import { componentName } from './file'

Merely what if you apply default export?

export default componentName        

In that example, you lot'd take to import it without curly braces, but the naming is non of import. You lot could do it like this:

import componentName from './file' //ok import someOtherName from './file' //ok import { componentName } from './file' //wrong!

Animated.View fault

Invariant Violation: [453,"RCTView",1,
{"width":250,"height":fifty,"backgroundColor":4289781990,"opacity":i}] is non usable as a native method statement

This fault is located at:

in RCTView (at file.js:27)
in FadeInView (at file.js:42)
in RCTView (at file.js:41)
in _default (at App.js:29)
in RCTScrollContentView (at ScrollView.js:1038)
in RCTScrollView (at ScrollView.js:1178)
in SafeAreaView (at App.js:24)
in App (at renderApplication.js:40)
in RCTView (at AppContainer.js:101)
in RCTView (at AppContainer.js:119)
in AppContainer (at renderApplication.js:39)

Developers frequently encounter this error when using animated elements from React Native. It's one of the trickiest errors you'll see, and the prompt might look slightly different depending on the use case.

Although the message is confusing, the error is caused by a unproblematic error: when creating an animated component, y'all take to create an element (due east.g., View), similar this:

<Blithe.View>

If y'all apply a normal view, the to a higher place fault will pop up.

It can be difficult to identify this error, and understanding it can save you a lot of time. There's an result for this listed in the React Native repository among other annoying errors to fix, and the team is expected to improve on information technology in an upcoming release.

Autolinking error

error React Native CLI uses autolinking for native dependencies, only the following modules are linked manually:

…

This is probable happening when upgrading React Native from below 0.threescore to 0.60 or above. Going forrad, yous can unlink this dependency via "react-native unlink <dependency>" and it will be included in your app automatically. If a library isn't compatible with autolinking, disregard this message and notify the library maintainers.

As of React Native version 0.sixty, we no longer need to utilize the react-native link command, which makes the process of setting up an app much easier. However, it tin can also trigger new errors, peculiarly if you're using an quondam library that doesn't back up the autolinking feature.

If you lot used react-native link in your 0.threescore+ project, run react-native unlink and then try running your app. If yous didn't employ the command but received the error anyway, it'south likely that one of your dependencies is not suitable for autolinking. If that's the cause, you can try using patch-parcel to prepare it on your own.

Exist sure to create a pull request with your solution to the library repository — you may be able to help others salvage a lot of time.

Null in the image element

JSON value '<null>' of blazon NSNull cannot be converted to NSString

This fault occurs when an prototype element has a URI set as nil.

<Image source={{ uri: nada }} />        

Information technology can be especially difficult to tackle this mistake if the URI you want to open is fetched from the backend and y'all're non sure whether it's a proper link or cipher.

URI versus URL in the image chemical element

When displaying a remote image in the image element, you should name the source object equally a URI, like this:

<Paradigm source={{ uri: 'https://facebook.github.io/react-native/img/homepage/phones.png' }} />

If you mistakenly name it "URL" instead of the "URI," the image will be displayed on the iOS device, but it will fail silently on the Android device. Being aware of this error could save you a lot of fourth dimension and energy debugging.

Cord exterior text

Invariant Violation: Text strings must be rendered within <Text> component.

This mistake is located at:

in a (at App.js:29)
in RCTScrollContentView (at ScrollView.js:1038)
in RCTScrollView (at ScrollView.js:1178)
in ScrollView (at App.js:25)
in RCTSafeAreaView (at SafeAreaView.js:55)
in SafeAreaView (at App.js:24)
in App (at renderApplication.js:40)
in RCTView (at AppContainer.js:101)
in RCTView (at AppContainer.js:119)
in AppContainer (at renderApplication.js:39)

This fault message is adequately straightforward, and you can run into that information technology'southward located in the app.js file on line 29, but it's withal worth mentioning the possible causes.

If y'all run into this error, you lot may accept forgotten to wrap your string with a Text component or introduced a typo that rendered your component unrecognizable. The latter is the most common cause — an additional subclass here, a superfluous comma in that location. These typos can be hard to spot, even if we know where to look.

Information technology would exist squeamish if, in hereafter versions, the mistake bulletin could include more useful data, such as the specific string that caused the issue.

Dependencies error

Error: undefined Unable to resolve module `@babel/runtime/helpers/interopRequireDefault` from `App.js`: @babel/runtime/helpers/interopRequireDefault could not be found within the project.

If y'all are sure the module exists, endeavor these steps:
1. Articulate watchman watches: watchman picket-del-all
2. Delete node_modules: rm -rf node_modules and run yarn install
3. Reset Metro's enshroud: yarn start ––reset-cache
four. Remove the cache: rm -rf /tmp/metro-*

If an error similar this appears seemingly out of nowhere, the first suspects should exist NPM or Yarn and dependencies in the node_modules folder.

Commencement, you can attempt reinstalling the whole dependencies directory. If a major dependency is somehow changed in your repository, information technology could cause issues. Run the command in the main project directory where you see the node_modules folder to remove and install them again.

rm -rf node_modules && yarn

If this doesn't work, you lot tin try following the steps outlined in the error message. Hither is a slightly modified control prepare to copy to your terminal:

watchman scout-del-all && rm -rf /tmp/haste-map-react-native-packager-* && rm -rf /tmp/metro-bundler-enshroud-* && rm -rf node_modules/ && yarn cache clean && yarn

This will clear watchman watches, reset the metro bundler cache, remove the haste cache, reinstall the whole node_modules directory, and clear the yarn cache.

Additional troubleshooting for Android and iOS

If you still have errors, you could try cleaning your project. The steps will vary depending on the platform you are developing on.

Android

Endeavour immigration the Gradle cache past typing the following command from the principal project directory.

cd android && ./gradlew clean

iOS

Try cleaning your project if you're opening it from the XCode. Click "Product" and "Make clean" from the upper carte bar.

You may likewise want to endeavor running pod deintegrate in the ios directory to remove pods completely, so running pod install again.

Finally, removing derived data can be very helpful:

rm -rf ~/Library/Developer/Xcode/DerivedData/*

Summary

Now you should exist able to address seven of the almost mutual bugs you're probable to come across while developing a React Native app. Some of them are being stock-still equally you read this article, and mistake letters will evolve to be more descriptive and informative every bit new versions are released. Merely for at present, nosotros need to work with what we've got. Knowing the context backside these errors tin save you a lot of painful time spent debugging. After all, while most of these errors are difficult to spot, they're commonly easy to fix if you know what you lot're looking for.

Full visibility into production React apps

Debugging React applications tin be difficult, especially when users experience problems that are difficult to reproduce. If you lot're interested in monitoring and tracking Redux state, automatically surfacing JavaScript errors, and tracking irksome network requests and component load time, try LogRocket.

LogRocket is similar a DVR for web and mobile apps, recording literally everything that happens on your React app. Instead of guessing why issues happen, you can aggregate and written report on what state your application was in when an issue occurred. LogRocket also monitors your app's performance, reporting with metrics like client CPU load, client retentiveness usage, and more.

The LogRocket Redux middleware bundle adds an extra layer of visibility into your user sessions. LogRocket logs all actions and country from your Redux stores.

Modernize how yous debug your React apps — start monitoring for gratuitous.

LogRocket: Instantly recreate issues in your React Native apps.

LogRocket is a React Native monitoring solution that helps yous reproduce problems instantly, prioritize bugs, and understand performance in your React Native apps.

LogRocket also helps y'all increase conversion rates and product usage by showing you exactly how users are interacting with your app. LogRocket's product analytics features surface the reasons why users don't complete a particular menstruum or don't prefer a new feature.

Beginning proactively monitoring your React Native apps — try LogRocket for costless.

Source: https://blog.logrocket.com/common-bugs-in-react-native/

Posted by: cephaswhersely1982.blogspot.com

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