How to do logging in React Native

Question

How can I log a variable in React Native  like using console log when developing for web

User · Answer

Use console debug  text     You will see the logs inside the terminal   Steps    Run the application    react-native run-ios          For iOS react-native run-android      For Android    Run the logger    react-native log-ios          For iOS react-native log-android      For Android

User · Answer

There are 3 methods that I use to debug when developing React Native apps    console log    shows in console console warn    shows in yellow box bottom of application alert    shows as a prompt just like it does in web

User · Answer

Use console log  console warn etc   As of React Native 0 29 you can simply run the following to see logs in the console     react-native log-ios   react-native log-android

User · Answer

You use the same thing that is used for regular web  The console command also works in this case  For example  you can use console log    console warn     console clear   etc    You can use Chrome Developer to use the console command when you re logging while you are running your React Native app

User · Answer

There is a debugger tool that you can see you console message on top of you device screen  So you don t need connecting to any remote debugger that will slow down your animation or anything  Can check here   https   github com fwon RNVConsole  Or use expo to have a try https   snack expo io SklJHMS3S

User · Answer

If you are on osx and using an emulator  you can view your console logs directly in safari web inspector   Safari    Development    Simulator -  your simulator version here     JSContext

User · Answer

I had the same issue  console messages were not appearing in XCode s debug area  In my app I did cmd-d to bring up the debug menu  and remembered I had set  Debug in Safari  on   I turned this off  and some messages were printed to the output message  but not my console messages  However  one of the log messages said      DEV       false  development-level warning are OFF  performance optimizations are ON    This was because I had previously bundled my project for testing on a real device with the command   react-native bundle --minify   This bundled without  dev-mode  on  To allow dev messages include the --dev flag   react-native bundle --dev   And console log messages are back  If you aren t bundling for a real device  don t forget to re-point jsCodeLocation in AppDelegate m to localhost  I did

User · Answer

You can use Reactotron also  it will give you lot more functionality than just logging  https   github com infinitered reactotron

User · Answer

I prefer to recommend you guys using React Native Debugger  You can download and install it by using this command   brew update  amp  amp  brew cask install react-native-debugger  or  Just check the link below   https   github com jhen0409 react-native-debugger  Happy Hacking

User · Answer

console log   is the easy way to debug your code but it need to be use with arrow function or bind   while displaying any state  You may find the link useful

User · Answer

console log can be used for any JS project  If you running the app in localhost then obviously it is similar any to any javascript project  But while using simulator or any device  connect that simulator to our localhost and we can see in the console

User · Answer

This is where Chrome Developer Tools are your friend   The following steps should get you to the Chrome Developer Tools  where you will be able to see your console log statements   Steps   Install Google Chrome  if you have not already Run app using react-native run-android or react-native run-ios Open developer menu   Mac    D  for iOS or  M for Android iOS Windows Linux  Shake Android phone  Select Debug JS Remotely This should launch the debugger in Chrome In Chrome  Tools - gt  More Tools - gt  Developer Options and make sure you are on the console tab   Now whenever a console log statement is executed  it should appear in Chrome Dev Tools  The official documentation is here

User · Answer

console log works    By default on iOS  it logs to the debug pane inside Xcode    From the IOS simulator press    D  and press Remote JS Debugging  This will open a resource  http   localhost 8081 debugger-ui on localhost  From there use Chrome Developer tools javascript console to view console log

User · Answer

You can use remote js debugly option from your device or you can simply use react-native log-android and react-native log-ios for ios

User · Answer

There is normally two scenarios where we need debugging    When we facing issues related to data and we want to check our data and debugging related to data in that case console log  data    data   and debug js remotely is the best option  Other case is the UI and styles related issues where we need to check styling of the component in that case react-dev-tools is the best option   both of the methods mention here

User · Answer

There are two options to debug or get output of  your react native application when using      Emulator or Real Device   For First Using Emulator  use     react-native log-android  or react-native log-ios   to get the log output      on real device shake your device   so the menu will come from where you select remote debug and it will open this screen in your browser  so you can see your log output in console tab

User · Answer

Press  command   control   Z  in Xcode Simulator  choose Debug JS Remotely  then press  command   option   J  to open Chrome developer tools   Xcode Simulator Img  refer Debugging React Native Apps

User · Answer

Where you want to log data use  console log  quot data quot    And to print this log in terminal use command for android  npx react-native log-android  and for iOS  npx react-native log-ios

User · Answer

You can do this in 2 methods   1  by using warn   console warn  somthing    this state Some Sates of variables     2  By using Alert  This is not good each times if it reaches alert then each time pop will be opened so if doing looping means not preferable to use this  Import the  Alert  from  react-native        use this alert    Alert alert  somthing    this state Some Sates of variables

User · Answer

react-native-xlog module that can help you is WeChat s Xlog for react-native  That can output in Xcode console and log file  the Product log files can help you debug   Xlog verbose  tag    log    Xlog debug  tag    log    Xlog info  tag    log    Xlog warn  tag    log    Xlog error  tag    log    Xlog fatal  tag    log

User · Answer

Something that just came out about a month ago is  Create React Native App   an awesome boilerplate that allows you  with minimal effort  to show what your app looks like live on your mobile device  ANY with a camera  using the Expo app  It not only has live updates  but it will allow you to see the console logs in your terminal just like when developing for the web  rather than having to use the browser like we did with React Native before   You would  of course  have to make a new project with that boilerplate    but if you need to migrate your files over  that shouldn t be a problem  Give it a shot   Edit  Actually it doesn t even require a camera  I said that for scanning a QR code  but you can also type out something to sync it up with your server  not just a QR code

User · Answer

Every developer facing this issue of debugging with the react native  even I faced too and I refer this and solution is sufficient for me at initial level  it cover few ways that help us to try and use what ever comfortable with us   Debugging with console log Debugging code  logic  with Nuclide Debugging code logic  with Chrome Use Xcode to debug GUI   https   codeburst io react-native-debugging-tools-3a24e4e40e4

User · Answer

console log   is the best and simple way to see your log on console when you use remote js debugger from your developer menu

User · Answer

Visual Studio Code has a decent debug console that can show your console log     VS Code is  more often than not  React Native friendly

User · Answer

Users with Windows and Android Studio   You re going to find it under Logcat in Android Studio  There are a lot of logging messages that show up here  so it may be easier for you to create a filter for  ReactNativeJS  which will only show your console log messages that are created inside your react native application

User · Answer

Pre React Native 0 29  run this in the console   adb logcat   S ReactNative V ReactNativeJS V  Post React Native 0 29  run   react-native log-ios  or   react-native log-android  As Martin said in another answer   This shows all console log    errors  notes  etc  and causes zero slow down

User · Answer

If you use ios simulator you can open system console log on MAC     space and type  quot console quot  - gt  press  quot Enter quot  to open system console log then select your simulator

User · Answer

Use react native debugger for logging and redux store https   github com jhen0409 react-native-debugg  Just download it and run as software then enable Debug mode from the simulator   It supports other debugging feature just like element in chrome developer tools  which helps to see the styling provided to any component   Last complete support for redux dev tools

User · Answer

There are multiple ways to log  console warn   will through the log in the mobile screen itself It can be useful if you want to log small things and dont want to bother opening console  Other is console log    for which you will have to open browser s console to view the logs With the newer react native 0 62  you can see the log in node itself  So they ve made it pretty easier to view logs in newer version

User · Answer

Just console log  debug      And run it you can see the log in the terminal cd prompt

User · Answer

There are several ways to achieve this  I am listing them and including cons in using them also  You can use     console log and view logging statements on  without opting out for remote debugging option from dev tools  Android Studio and Xcode  or you can opt out for remote debugging option and view logging on chrome dev tools or vscode or any other editor that supports debugging  you have to be cautious as this will slow down the process as a whole  You can use console warn but then your mobile screen would be flooded with those weird yellow boxes which might or might not be feasible according to your situation  Most effective method that I came across is to use a third party tool  Reactotron  A simple and easy to configure tool that enables you to see each logging statement of different levels  error  debug  warn  etc    It provides you with the GUI tool that shows all the logging of your app without slowing down the performance

User · Answer

Chrome Devtool is the best and easiest way for logging and debugging

User · Answer

Put console log  My log text   in your code go to your command Line tools position oneself in its development folder   In Android    write this command   React-native log-android   In IOS    write this command   React-native log-ios

User · Answer

Its so simple to get logs in React-Native   Use console log and console warn  console log  character   parameter   console warn  character   parameter    This log you can view in browser console  If you want to check device log or say production APK log you can use  adb logcat  adb -d logcat

User · Answer

Development Time Logging  For development time logging  you can use console log     One important thing  if you want to disable logging in production mode  then in Root Js file of app  just assign blank function like this - console log      It will disable whole log publishing throughout app altogether  which actually required in production mode as console log consumes time     Run Time Logging  In production mode  it is also required to see logs when real users are using your app in real time  This helps in understanding bugs  usage and unwanted cases  There are many 3rd party paid tools available in the market for this  One of them which I ve used is by Logentries   The good thing is that Logentries has got React Native Module as well  So  it will take very less time for you to enable Run time logging with your mobile app

[logging] How to do logging in React Native?

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