react-native: SyntaxError: Strict mode does not allow function declarations in a lexically nested statement on a newly created app

I’ve found how to fix it

open node_modules\react-native\Libraries\Core\InitializeCore.js line 112 change function handleError(e, isFatal) to var handleError = function(e, isFatal) then do npm start – --reset-cache

hope that it will be fixed soon I have created pull request for that https://github.com/facebook/react-native/pull/11390

and for me it works without any error if remote debugging is enabled

If you make a search, you can see that many many people have the exact same problem and many of they change the pc, or reinstall their OS to make rn work again.

Running React-native 0.35 and having same issue – this is what helped to me

• In node_modules/react-native/Libraries/BatchedBridge/BatchedBridgedModules/NativeModules.js

  function normalizePrefix(moduleName: string) ...

  REPLACE WITH:

  const normalizePrefix = function(moduleName: string)

• In /node_modules/react-native/Libraries/Utilities/UIManager.js:

  function normalizePrefix(moduleName: string) ...

  REPLACE WITH:

  const normalizePrefix = function(moduleName: string)

• In /node_modules/react-native/…/InitializeJavascriptAppEngine.js:

  function handleError(e, isFatal) ...

  REPLACE WITH:

  var handleError = function(e, isFatal)

then do npm start – --reset-cache

@lohithananda On the android emulator, press Ctrl+M to open the dev menu, and then choose start Rote JS Debugging, it will open a new tab in chrome, keep it open.

Shipped to 0.39.2.

Fuck my life

@LitbLeo looks like this code is in another place in 0.34.1 try to open node_modules\react-native\Libraries\JavaScriptAppEngine\Initialization\InitializeJavaScriptAppEngine.js line 120 and change function handleError(e, isFatal) to var handleError = function(e, isFatal) then do npm start – --reset-cache

I can’t find node_modules\react-native\Libraries\Core\InitializeCore.js,Whta to do? @ @Taximan @

You can revert update to RN v0.39 also … v0.38 works nice 😃

Another way to “fix” this, if you can’t update to a newer version yet, is to enable JS Minify mode in Dev Settings. Works on version 0.34.0.

I see the same and only for Android version. When debug is enabled everything works.

I’ve tried to understand the cause of the problem, jumping from commit to commit back in history and it looks like the reason of problem is the latest release of babel. https://github.com/babel/babel/releases/tag/v6.20.0

With babel 6.18.0 in yarn.lock file everything is okay. When I remove yarn.lock and install it again one of sub-dependencies fetches the latest version of babel and the problem appears.

my react-native version is “0.31.0”。set emulator dubug js remote works,but my emulator runs slowly.I’m finding another way to save it. God bless me.

Me too, same error. Nothing of the previous suggested methods work, even if i am able to execute the app if remote js debug is active

+1

For everyone who still facing this error try another workaround. Edit node_modules/react-native/Libraries/Utilities/UIManager.js file and replace:

function normalizePrefix(moduleName: string): string { with var normalizePrefix = function (moduleName: string): string {

This worked for me, referencing superfe issue

This is occurring in 0.46.4.

07-31 00:07:35.786 4831-5376/com.nycevents E/ReactNativeJNI: Got JS Exception: SyntaxError: Strict mode does not allow function declarations in a lexically nested statement. (http://10.0.2.2:8081/index.android.bundle?platform=android&dev=true&hot=false&minify=false:1583) 07-31 00:07:35.786 4831-5376/com.nycevents E/unknown:React: Exception in native call from JS com.facebook.react.devsupport.JSException: SyntaxError: Strict mode does not allow function declarations in a lexically nested statement. (http://10.0.2.2:8081/index.android.bundle?platform=android&dev=true&hot=false&minify=false:1583) at com.facebook.react.bridge.queue.NativeRunnable.run(Native Method) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at com.facebook.react.bridge.queue.MessageQueueThreadHandler.dispatchMessage(MessageQueueThreadHandler.java:31) at android.os.Looper.loop(Looper.java:148) at com.facebook.react.bridge.queue.MessageQueueThreadImpl$3.run(MessageQueueThreadImpl.java:194) at java.lang.Thread.run(Thread.java:818) Caused by: com.facebook.jni.CppException: SyntaxError: Strict mode does not allow function declarations in a lexically nested statement. (http://10.0.2.2:8081/index.android.bundle?platform=android&dev=true&hot=false&minify=false:1583) at com.facebook.react.bridge.queue.NativeRunnable.run(Native Method)  at android.os.Handler.handleCallback(Handler.java:739)  at android.os.Handler.dispatchMessage(Handler.java:95)  at com.facebook.react.bridge.queue.MessageQueueThreadHandler.dispatchMessage(MessageQueueThreadHandler.java:31)  at android.os.Looper.loop(Looper.java:148)  at com.facebook.react.bridge.queue.MessageQueueThreadImpl$3.run(MessageQueueThreadImpl.java:194)  at java.lang.Thread.run(Thread.java:818)  07-31 00:07:35.788 4831-5376/com.nycevents E/unknown:React: Exception in native call java.lang.RuntimeException: Error calling AppRegistry.runApplication at com.facebook.react.bridge.queue.NativeRunnable.run(Native Method) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at com.facebook.react.bridge.queue.MessageQueueThreadHandler.dispatchMessage(MessageQueueThreadHandler.java:31) at android.os.Looper.loop(Looper.java:148) at com.facebook.react.bridge.queue.MessageQueueThreadImpl$3.run(MessageQueueThreadImpl.java:194) at java.lang.Thread.run(Thread.java:818) Caused by: com.facebook.jni.CppException: Could not get BatchedBridge, make sure your bundle is packaged correctly at com.facebook.react.bridge.queue.NativeRunnable.run(Native Method)  at android.os.Handler.handleCallback(Handler.java:739)  at android.os.Handler.dispatchMessage(Handler.java:95)  at com.facebook.react.bridge.queue.MessageQueueThreadHandler.dispatchMessage(MessageQueueThreadHandler.java:31)  at android.os.Looper.loop(Looper.java:148)  at com.facebook.react.bridge.queue.MessageQueueThreadImpl$3.run(MessageQueueThreadImpl.java:194)  at java.lang.Thread.run(Thread.java:818) 

Just activate a JS Minify option in the Emulator Dev Settings

In Emulator: Menu > Dev Settings > JS Minify ☑(active)

Here it worked only with this, I hope it has helped;)

Same happens in v0.46.1

Hey, guys, I found the same issue on RN 45.1 install on ios 9.3. But it works fine on ios 10.3 If there has anyone get into this problem?

I have an app which till yesterday was working properly and i have to implement new plugin so i switched to different branch on my git flow and installed that plugin, but i had got to make build for client it was the urgent requirement so i switched back to develop branch and removed node_modules folder and did NPM install but after that i started getting following issue:SyntaxError: Strict mode does not allow function declarations in a lexically nested statement I checked the work around solution you provided about opening node_modules\react-native\Libraries\Core\InitializeCore.js line 112 and making required changes. but in my react-native\Libraries\ folder in node_modules i am not able to see Core folder nor am i able to find InitializeCore.js in whole react-native folder.

Following are my versions of react & react-native mentioned in package.json: “react”: “15.3.1”, “react-native”: “0.34.1”,

And the application has to be uploaded to play store in next 2 days. So i am not in a position to upgrade react-native version also.

Please suggest some solution. Stuck badly.

@karpoff I did that still I’m getting the same error But if I run using debug js remotely it works fine. But I had to create offline app for testing multiple devices as well as putting it in app store. using: "native-base": "0.5.15", "react": "15.3.1", "react-native": "0.33.1",

🥇 Fixed on React Native 0.40.0

“react”: “15.3.1”, “react-native”: “^0.34.1”, in node_modules/react-native/Libraries/Utilities/UIManager.js remove ‘use strict’;

add gulp task

gulp.task('fix', () =>
    gulp.src('node_modules/react-native/Libraries/Utilities/UIManager.js')
        .pipe(replace(/\'use\ strict\'\;/g, ''))
        .pipe(gulp.dest('node_modules/react-native/Libraries/Utilities/')));

and postinstall in package.json 's scripts

  "scripts":{
    postinstall: "gulp fix",
    ...
  }

Updated react-native to version 0.47.0 and it fixed it.

I’m facing the same issue @jrempel1. Any fix?

NOTE: This problem occurs just in Android.

I’ve just disabled “JS Dev Mode” and enabled “JS Minify”. It seems to work…

For the lazy:

# formatted for OSX: http://stackoverflow.com/questions/19456518/invalid-command-code-despite-escaping-periods-using-sed
sed -i '' -e 's/function normalizePrefix(moduleName: string)/const normalizePrefix = function(moduleName: string)/g' ./node_modules/react-native/Libraries/BatchedBridge/BatchedBridgedModules/NativeModules.js

sed -i '' -e 's/function normalizePrefix(moduleName: string)/const normalizePrefix = function(moduleName: string)/g' ./node_modules/react-native/Libraries/Utilities/UIManager.js

sed -i '' -e 's/function handleError(e, isFatal)/var handleError = function(e, isFatal)/g' ./node_modules/react-native/Libraries/JavaScriptAppEngine/Initialization/InitializeJavaScriptAppEngine.js

# check that it worked
grep normalize ./node_modules/react-native/Libraries/BatchedBridge/BatchedBridgedModules/NativeModules.js

grep normalize ./node_modules/react-native/Libraries/Utilities/UIManager.js

grep handleError ./node_modules/react-native/Libraries/JavaScriptAppEngine/Initialization/InitializeJavaScriptAppEngine.js

@quietbits Thanks,this way can fix this issue!

@taozijie @Taximan Me too,what to do?My version is 0.34.1

Works fine on with react-native version 0.39.2.

@karpoff Hi, I’m having trouble locating the file. I do not have the Libraries folder at all under …/npm/node-modules/react-native-cli…there’s another node-modules folder in it which doesn’t have the Libraries folder either

@lednhatkhanh i am working on the real android device

@niranjan-b-prajapati update react and react-native to “react”: “~15.4.0”, “react-native”: “^0.41.2” Delete node-modules of your project and install npm. For me it works.

I think you might have to do npm upgrade, but that would upgrade all of your node modules, not just react native. Otherwise I would just do Karpoff’s solution. It’s the 5th response from the top.

Edit According to the docs https://facebook.github.io/react-native/releases/0.28/docs/upgrading.html react-native upgrade should work. I don’t know why it wouldn’t when you ran it.

This bug has been fixed. If you react-native init a new project now, you will see that this code/bug has been changed.

Argh! My bad! Thanks @EQuimper

I’ve been running a day running my first application and I can not believe the mistake was this …

It works for me too…

Thanks @karpoff

Issue exists on react native v0.39.1 Solution suggested by @karpoff works Thank you so much