ReactJS

React Native Crash Undefined is not an object (Evaluating ‘Sn[e]’)

React Native Crash Undefined is not an object (Evaluating ‘Sn[e]’)

Any one facing react native build issue? I am trying to generate debug build but its crashing when the app is launched . The exception has no useful information. I was facing the same issue with

sudo react-native run-android

 

But that got resolved after upgrading RN from 0.48 to 0.55(latest Stable Version). But the crash remain same for the apk generated using

sudo gradlew assembleDebug

The crash is similar to https://github.com/facebook/react-native/issues/16745

please see screenshot

ReactNative Undefined Not an object evaluating

ReactNative Undefined Not an object evaluating

Solution: Generating React Native Android Release and Debug Builds

1. If any one facing issue with generating ReactNative android build then do not forget to follow below steps

2. Update your key store details as given here

3. Then explicitly bundle the assets using below command

react-native bundle --platform android --dev false --entry-file index.android.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res/ 

4. Generate the build using gradle

cd android && ./gradlew assembleRelease

Note: for release build I am facing another issue as follows

Error in Release build :

FAILURE: Build failed with an exception.

* What went wrong:
Failed to capture snapshot of input files for task ‘bundleReleaseJsAndAssets’ property ‘$1’ during up-to-date check.
> Failed to create MD5 hash for file ‘/Development/SourceCode/MobApp/testApp/root-state/sock’.

* Try:
Run with –stacktrace option to get the stack trace. Run with –info or –debug option to get more log output.

* Get more help at https://help.gradle.org

BUILD FAILED in 2s

To generate debug build

cd android && ./gradlew assembleDebug

 

Credits : SO Post

React Native react-navigation props.navigation.navigate(“DrawerOpen”) doesn’t work

React Native react-navigation props.navigation.navigate(“DrawerOpen”) doesn’t work

If you are using react-navigation version “1.0.0-beta.11” then the following apis works fine

props.navigation.navigate('DrawerOpen'); // open drawer
props.navigation.navigate('DrawerClose'); // close drawer

 

If you are using react-navigation version “2.0.0-rc.9” then following apis works fine

props.navigation.openDrawer();
props.navigation.closeDrawer();
props.navigation.toggleDrawer();

 

Read More About React-Navigation Package : react-navigation performance issues

Typical React Native Navigation issues people facing for this

navigation.navigate(‘DrawerOpen’) doesn’t work

DrawerToggle not working on Android #2760

Drawer Menu doesn’t work in react-native

React Native react-navigation navigation.navigate.reset doesn’t work

React Native react-navigation navigation.navigate.reset doesn’t work

1. If you are using react-navigation version “1.0.0-beta.11” then kindly use the below code to reset navigation stack

const resetAction = NavigationActions.reset({
    index: 0,
    key: null,
    actions: [ NavigationActions.navigate({ routeName: 'Home' }) ],
  });
  navigation.dispatch(resetAction);

//Note key: null is very important here.

Reference: github post by react navigation contributor 
2. If you are using react-navigation(v2) version “2.0.0-rc.9” then kindly use the below code to reset navigation stack

const resetAction = StackActions.reset({
    index: 0,
    key: null,
    actions: [ NavigationActions.navigate({ routeName: 'DrawerStack' }) ],
  });
  navigation.dispatch(resetAction);

 

Read More On React-Navigation : Typical issues of react-navigation

React Native: Ejecting Expo To Regular React Native Project.

React Native: Ejecting Expo To Regular React Native Project.

Before explaining the steps for eject from expo, I would like to thank the expo community who has done really a great job, it was nightmare for us to start with ReactNative initially without expo. Expo has done remarkable job and simplified the whole process to us. So we should thank expo community for that. But Expo has come up with its own limitations, it is really difficult to go forward with those limitations, hence ejecting from expo is must.

Follow below steps and find the issues listed in each step and the solutions for the issues faced during eject process. Follow all the below steps

1. npm run eject

<span style="color: #000000;">? How would you like to eject from create-react-native-app? (Use arrow keys)
❯ React Native: I'd like a regular React Native project. 
  ExpoKit: I'll create or log in with an Expo account to use React Native and the Expo SDK. 
  Cancel: I'll continue with my current project structure. 
Choose 1st option</span>

2. then run the command

react-native run-android
Building and installing the app on the device (cd android && ./gradlew installDebug)…

Problem:
FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring project ‘:app’.
> SDK location not found. Define location with sdk.dir in the local.properties file or with an ANDROID_HOME environment variable.

* Try:
Run with –stacktrace option to get the stack trace. Run with –info or –debug option to get more log output.

BUILD FAILED

Total time: 45.174 secs
Could not install the app on the device, read the error above for details.
Make sure you have an Android emulator running or a device connected and have
set up your Android development environment:
https://facebook.github.io/react-native/docs/android-setup.html

Solution:
Create local.properties in the andoid project folder and save the below content in that
sdk.dir = /Users/USERNAME/Library/Android/sdk
USERNAME: USERNAME should be your maachine user name

3. run the command

$ sudo react-native run-android

Problem:

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ‘:app:installDebug’.
> com.android.builder.testing.api.DeviceException: No connected devices!

* Try:
Run with –stacktrace option to get the stack trace. Run with –info or –debug option to get more log output.

BUILD FAILED

Total time: 6.945 secs
Could not install the app on the device, read the error above for details.
Make sure you have an Android emulator running or a device connected and have
set up your Android development environment:
https://facebook.github.io/react-native/docs/android-setup.html

   Solution : Use proper cable and connect your device, enable debug mode in your android device. this is problem with some devices, do not spend time on this, because you will face bigger problems later 🙂 so either change the device or try with different cable.

4. Problem
com.android.ddmlib.InstallException: Failed to install all
at com.android.ddmlib.SplitApkInstaller.install(SplitApkInstaller.java:89)
at com.android.ddmlib.Device.installPackages(Device.java:904)
at com.android.builder.testing.ConnectedDevice.installPackages(ConnectedDevice.java:137)
at com.android.build.gradle.internal.tasks.InstallVariantTask.install(InstallVariantTask.java:134)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:75)
at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.doExecute(AnnotationProcessingTaskFactory.java:228)
at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:221)
at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:210)
at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:621)
at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:604)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:80)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:61)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:46)
at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExecuter.execute(PostExecutionAnalysisTaskExecuter.java:35)
at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:66)
at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:58)
at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:52)
at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:52)
at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:53)
at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:43)
at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:203)
at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:185)
at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.processTask(AbstractTaskPlanExecutor.java:66)
at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.run(AbstractTaskPlanExecutor.java:50)
at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor.process(DefaultTaskPlanExecutor.java:25)
at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter.execute(DefaultTaskGraphExecuter.java:110)
at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTaskExecutionAction.java:37)
at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:37)
at org.gradle.execution.DefaultBuildExecuter.access$000(DefaultBuildExecuter.java:23)
at org.gradle.execution.DefaultBuildExecuter$1.proceed(DefaultBuildExecuter.java:43)
at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildExecutionAction.java:32)
at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:37)
at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:30)
at org.gradle.initialization.DefaultGradleLauncher$4.run(DefaultGradleLauncher.java:153)
at org.gradle.internal.Factories$1.create(Factories.java:22)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:91)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:53)
at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:150)
at org.gradle.initialization.DefaultGradleLauncher.access$200(DefaultGradleLauncher.java:32)
at org.gradle.initialization.DefaultGradleLauncher$1.create(DefaultGradleLauncher.java:98)
at org.gradle.initialization.DefaultGradleLauncher$1.create(DefaultGradleLauncher.java:92)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:91)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:63)
at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:92)
at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:83)
at org.gradle.launcher.exec.InProcessBuildActionExecuter$DefaultBuildController.run(InProcessBuildActionExecuter.java:99)
at org.gradle.tooling.internal.provider.ExecuteBuildActionRunner.run(ExecuteBuildActionRunner.java:28)
at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35)
at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:48)
at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:30)
at org.gradle.launcher.exec.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:81)
at org.gradle.launcher.exec.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:46)
at org.gradle.launcher.exec.DaemonUsageSuggestingBuildActionExecuter.execute(DaemonUsageSuggestingBuildActionExecuter.java:51)
at org.gradle.launcher.exec.DaemonUsageSuggestingBuildActionExecuter.execute(DaemonUsageSuggestingBuildActionExecuter.java:28)
at org.gradle.launcher.cli.RunBuildAction.run(RunBuildAction.java:43)
at org.gradle.internal.Actions$RunnableActionAdapter.execute(Actions.java:173)
at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:239)
at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:212)
at org.gradle.launcher.cli.JavaRuntimeValidationAction.execute(JavaRuntimeValidationAction.java:35)
at org.gradle.launcher.cli.JavaRuntimeValidationAction.execute(JavaRuntimeValidationAction.java:24)
at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:33)
at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:22)
at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:205)
at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:169)
at org.gradle.launcher.Main.doAction(Main.java:33)
at org.gradle.launcher.bootstrap.EntryPoint.run(EntryPoint.java:45)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.gradle.launcher.bootstrap.ProcessBootstrap.runNoExit(ProcessBootstrap.java:55)
at org.gradle.launcher.bootstrap.ProcessBootstrap.run(ProcessBootstrap.java:36)
at org.gradle.launcher.GradleMain.main(GradleMain.java:23)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.gradle.wrapper.BootstrapMainStarter.start(BootstrapMainStarter.java:30)
at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:127)
at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:61)
:app:installDebug FAILED

Solution:
update gradle version in build.gradle file of your android project
classpath ‘com.android.tools.build:gradle:3.0.1’

5.

Problem
Building and installing the app on the device (cd android && ./gradlew installDebug)…

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring root project ‘testApp’.
> Could not resolve all dependencies for configuration ‘:classpath’.
> Could not find com.android.tools.build:gradle:3.0.1.
Searched in the following locations:
https://jcenter.bintray.com/com/android/tools/build/gradle/3.0.1/gradle-3.0.1.pom
https://jcenter.bintray.com/com/android/tools/build/gradle/3.0.1/gradle-3.0.1.jar
Required by:
:testApp:unspecified

* Try:
Run with –stacktrace option to get the stack trace. Run with –info or –debug option to get more log output.

BUILD FAILED

Total time: 10.721 secs
Could not install the app on the device, read the error above for details.
Make sure you have an Android emulator running or a device connected and have
set up your Android development environment:
https://facebook.github.io/react-native/docs/android-setup.html

Solution:
add google() to your build script, as follows

buildscript {
    repositories {
        google()
        jcenter()
    }

 

6. Problem

FAILURE: Build failed with an exception.

* Where:
Build file ‘/testapp/android/build.gradle’ line: 5

* What went wrong:
A problem occurred evaluating root project ‘testApp’.
> Could not find method google() for arguments [] on repository container.

* Try:
Run with –stacktrace option to get the stack trace. Run with –info or –debug option to get more log output.

BUILD FAILED

Total time: 1.973 secs
Could not install the app on the device, read the error above for details.
Make sure you have an Android emulator running or a device connected and have
set up your Android development environment:
https://facebook.github.io/react-native/docs/android-setup.html

Solution:
in your android/gradle/wrapper/gradle-wrapper.properties file check whether you have gradle distribution version 4,
it should be as follow.

distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-all.zip

7. After this build success
8. Now facing Run-time exception of something like this

react android run Couldn’t find preset\ babel-preset-react native stage 0

error: bundling failed: “TransformError: D:\\path\\path\\project\\index.android.js: Unex
pected token ) (While processing preset: \”D:\\\\path\\\\path\\\\project\\\\node_modules
\\\\babel-preset-react-native\\\\index.js\”)”

Solution : Remove “babel-preset-react-native-stage-0/decorator-support” from your .bablerc file, Your bablerc file should look as follows

{
  "presets": [
    "react-native"
  ],
  "env": {
    "development": {
      "plugins": [
        "transform-react-jsx-source"
      ]
    }
  }
}

ReactJS/Redux Exception – Uncaught TypeError: Cannot read property ‘type’ of undefined

ReactJS/Redux Exception – Uncaught TypeError: Cannot read property ‘type’ of undefined

This issue might occur in many cases but one case which is hard to troubleshoot and debug is as given below. The typical call stack looks as follows for the exception

Uncaught TypeError: Cannot read property 'type' of undefined
at bundle.js:64518
    at bundle.js:64518
    at Array.forEach (&lt;anonymous&gt;)
    at x (bundle.js:64518)

One can make out nothing from the call stack, it looks meaningless. Hence the debugging will be tedious job in ReactJS . 

Solution for the above exception

check whether return statement with dispatch is missing in your redux action method.

  return (function (dispatch) {

  });

Your action should have return statement as shown above.

More Read About ReactJS:

Advantages of React Stateless Functional Components

Advantages of React Stateless Functional Components

Before reading this post, if you have not gone through what are functional components in Reactjs then kindly go through this post

In this post we will see what are the advantages of functional posts in React js. If you check your react js code, you will quickly figure out that many components do not actually need state, they do get data from parent as props and will render the information. In such a case why to introduce state and make it complicated? rather I would prefer calling a function which returns me a component. Isn’t it so simple ? React 14 introduced Functional Components, also called as stateless components and removed unnecessary complications. So let us explore what are the advantages of stateless components 

Advantages of React Functional/Stateless Components: Ref

1. More focused on presentation

React is forcing us to write components which are used only for presentational purpose, these components are useful for dumb presentational purpose only, that focus on UI rather than behaviour. Technically speaking its normal tendency to go for stateful components, doing that way we are making our code easily hackable where every damn component keeps its own local state. Functional components allowing us to have pure components which just focus on presentation. where as the state is maintained by few higher level components.

2. Gain in Performance

Stateless components will bring performance gain since there is no state and lifecycle of a component. React doesn’t need to have unnecessary check and memory allocations which eventually brings performance boost.

3. Clean and Optimised Code

Stateless components reduce lot of code, almost 20% – 30% reduction in code and hence the code will become clean and optimised.

4. Easy to debug

Functional components are pure components and helps your to analyse your code quickly and you no need to put log if assert calls everywhere to debug. 

React more on React

React More on ReactNative 

ReactJS : Functional or Stateless components

ReactJS : Functional or Stateless components

Many times you might come across a situation where React Component doesn’t need any state, which we call as stateless components. Thanks to React0.14 update, It introduced new types of react components with no state. 

React Stateless components are very much needed when the components is readonly doesn’t perform any operation other than just showing information.

How to Write React Functional component ?

React Functional Component Example: for stateless react component or a functional react component

const MessageBar = function(props) {
  return &lt;p&gt;Dear {props.username} you have completed the task successfully&lt;/p&gt;;
};

The same component can nicely be written in one line using ES2015 standard as follows

const MessageBar = ({ username }) =&gt; &lt;p&gt;Dear {username} user, you have successfully completed the task&lt;/p&gt;;

 

Conceptually components are like javascript functions here, they accept inputs as props, and return react elements. Functional components wherever required will also reduce load on redux since it is not required to maintain state for these components.

For more information on React functional components visit facebook react official site 

Check Advantages of React Functional Components

Also Check How to integrated Google Maps in reactJS : http://knowledge-cess.com/reactjs-google-map-component/