From fa33a3636374996a8f4351da319072b7ed2ccb3e Mon Sep 17 00:00:00 2001 From: Website Deployment Script Date: Tue, 9 May 2017 19:33:00 +0000 Subject: [PATCH] Updated docs for next --- releases/next/docs/debugging.html | 2 +- releases/next/img/ReactDevToolsDollarR.gif | Bin 0 -> 2159365 bytes 2 files changed, 1 insertion(+), 1 deletion(-) create mode 100644 releases/next/img/ReactDevToolsDollarR.gif diff --git a/releases/next/docs/debugging.html b/releases/next/docs/debugging.html index 96238fe0280..509cb099238 100644 --- a/releases/next/docs/debugging.html +++ b/releases/next/docs/debugging.html @@ -1,4 +1,4 @@ -Debugging
React Nativenext

The Basics

Guides

Guides (iOS)

Guides (Apple TV)

Guides (Android)

components

APIs

Debugging #

Enabling Keyboard Shortcuts #

React Native supports a few keyboard shortcuts in the iOS Simulator. They are described below. To enable them, open the Hardware menu, select Keyboard, and make sure that "Connect Hardware Keyboard" is checked.

Accessing the In-App Developer Menu #

You can access the developer menu by shaking your device or by selecting "Shake Gesture" inside the Hardware menu in the iOS Simulator. You can also use the Command⌘ + D keyboard shortcut when your app is running in the iPhone Simulator, or Command⌘ + M when running in an Android emulator.

The Developer Menu is disabled in release (production) builds.

Reloading JavaScript #

Instead of recompiling your app every time you make a change, you can reload your app's JavaScript code instantly. To do so, select "Reload" from the Developer Menu. You can also press Command⌘ + R in the iOS Simulator, or press R twice on Android emulators.

Automatic reloading #

You can speed up your development times by having your app reload automatically any time your code changes. Automatic reloading can be enabled by selecting "Enable Live Reload" from the Developer Menu.

You may even go a step further and keep your app running as new versions of your files are injected into the JavaScript bundle automatically by enabling Hot Reloading from the Developer Menu. This will allow you to persist the app's state through reloads.

There are some instances where hot reloading cannot be implemented perfectly. If you run into any issues, use a full reload to reset your app.

You will need to rebuild your app for changes to take effect in certain situations:

  • You have added new resources to your native app's bundle, such as an image in Images.xcassets on iOS or the res/drawable folder on Android.
  • You have modified native code (Objective-C/Swift on iOS or Java/C++ on Android).

In-app Errors and Warnings #

Errors and warnings are displayed inside your app in development builds.

Errors #

In-app errors are displayed in a full screen alert with a red background inside your app. This screen is known as a RedBox. You can use console.error() to manually trigger one.

Warnings #

Warnings will be displayed on screen with a yellow background. These alerts are known as YellowBoxes. Click on the alerts to show more information or to dismiss them.

As with a RedBox, you can use console.warn() to trigger a YellowBox.

YellowBoxes can be disabled during development by using console.disableYellowBox = true;. Specific warnings can be ignored programmatically by setting an array of prefixes that should be ignored: console.ignoredYellowBox = ['Warning: ...'];.

In CI/Xcode, YellowBoxes can also be disabled by setting the IS_TESTING environment variable.

RedBoxes and YellowBoxes are automatically disabled in release (production) builds.

Chrome Developer Tools #

To debug the JavaScript code in Chrome, select "Debug JS Remotely" from the Developer Menu. This will open a new tab at http://localhost:8081/debugger-ui.

Select Tools → Developer Tools from the Chrome Menu to open the Developer Tools. You may also access the DevTools using keyboard shortcuts (Command⌘ + Option⌥ + I on Mac, Ctrl + Shift + I on Windows). You may also want to enable Pause On Caught Exceptions for a better debugging experience.

Note: the React Developer Tools Chrome extension does not work with React Native, but you can use its standalone version instead. Read this section to learn how.

Debugging using a custom JavaScript debugger #

To use a custom JavaScript debugger in place of Chrome Developer Tools, set the REACT_DEBUGGER environment variable to a command that will start your custom debugger. You can then select "Debug JS Remotely" from the Developer Menu to start debugging.

The debugger will receive a list of all project roots, separated by a space. For example, if you set REACT_DEBUGGER="node /path/to/launchDebugger.js --port 2345 --type ReactNative", then the command node /path/to/launchDebugger.js --port 2345 --type ReactNative /path/to/reactNative/app will be used to start your debugger.

Custom debugger commands executed this way should be short-lived processes, and they shouldn't produce more than 200 kilobytes of output.

React Developer Tools #

With React Native 0.43 or higher, you can use the standalone version of React Developer Tools to debug the React component hierarchy. To use it, install the react-devtools package globally:

npm install -g react-devtools

Now run react-devtools from the terminal to launch the standalone DevTools app:

react-devtools

React DevTools

It should connect to your simulator within a few seconds.

Note: if you prefer to avoid global installations, you can add react-devtools as a project dependency. With Yarn, you can run yarn add --dev react-devtools, and then run yarn react-devtools from your project folder to open the DevTools. With npm, you can run npm install --save-dev react-devtools, add "react-devtools": "react-devtools" to the scripts section in your package.json, and then run npm run react-devtools from your project folder to open the DevTools.

Integration with React Native Inspector #

You can open the in-app developer menu and choose "Show Inspector". It will bring up an overlay that lets you tap on any UI element and see information about it:

React Native Inspector

However, when react-devtools is running, Inspector will enter a special collapsed mode, and instead use the DevTools as primary UI. In this mode, clicking on something in the simulator will bring up the relevant components in the DevTools:

React DevTools Inspector Integration

You can choose "Hide Inspector" in the same menu to exit this mode.

Performance Monitor #

You can enable a performance overlay to help you debug performance problems by selecting "Perf Monitor" in the Developer Menu.

+Debugging
React Nativenext

The Basics

Guides

Guides (iOS)

Guides (Apple TV)

Guides (Android)

components

APIs

Debugging #

Enabling Keyboard Shortcuts #

React Native supports a few keyboard shortcuts in the iOS Simulator. They are described below. To enable them, open the Hardware menu, select Keyboard, and make sure that "Connect Hardware Keyboard" is checked.

Accessing the In-App Developer Menu #

You can access the developer menu by shaking your device or by selecting "Shake Gesture" inside the Hardware menu in the iOS Simulator. You can also use the Command⌘ + D keyboard shortcut when your app is running in the iPhone Simulator, or Command⌘ + M when running in an Android emulator.

The Developer Menu is disabled in release (production) builds.

Reloading JavaScript #

Instead of recompiling your app every time you make a change, you can reload your app's JavaScript code instantly. To do so, select "Reload" from the Developer Menu. You can also press Command⌘ + R in the iOS Simulator, or press R twice on Android emulators.

Automatic reloading #

You can speed up your development times by having your app reload automatically any time your code changes. Automatic reloading can be enabled by selecting "Enable Live Reload" from the Developer Menu.

You may even go a step further and keep your app running as new versions of your files are injected into the JavaScript bundle automatically by enabling Hot Reloading from the Developer Menu. This will allow you to persist the app's state through reloads.

There are some instances where hot reloading cannot be implemented perfectly. If you run into any issues, use a full reload to reset your app.

You will need to rebuild your app for changes to take effect in certain situations:

  • You have added new resources to your native app's bundle, such as an image in Images.xcassets on iOS or the res/drawable folder on Android.
  • You have modified native code (Objective-C/Swift on iOS or Java/C++ on Android).

In-app Errors and Warnings #

Errors and warnings are displayed inside your app in development builds.

Errors #

In-app errors are displayed in a full screen alert with a red background inside your app. This screen is known as a RedBox. You can use console.error() to manually trigger one.

Warnings #

Warnings will be displayed on screen with a yellow background. These alerts are known as YellowBoxes. Click on the alerts to show more information or to dismiss them.

As with a RedBox, you can use console.warn() to trigger a YellowBox.

YellowBoxes can be disabled during development by using console.disableYellowBox = true;. Specific warnings can be ignored programmatically by setting an array of prefixes that should be ignored: console.ignoredYellowBox = ['Warning: ...'];.

In CI/Xcode, YellowBoxes can also be disabled by setting the IS_TESTING environment variable.

RedBoxes and YellowBoxes are automatically disabled in release (production) builds.

Chrome Developer Tools #

To debug the JavaScript code in Chrome, select "Debug JS Remotely" from the Developer Menu. This will open a new tab at http://localhost:8081/debugger-ui.

Select Tools → Developer Tools from the Chrome Menu to open the Developer Tools. You may also access the DevTools using keyboard shortcuts (Command⌘ + Option⌥ + I on Mac, Ctrl + Shift + I on Windows). You may also want to enable Pause On Caught Exceptions for a better debugging experience.

Note: the React Developer Tools Chrome extension does not work with React Native, but you can use its standalone version instead. Read this section to learn how.

Debugging using a custom JavaScript debugger #

To use a custom JavaScript debugger in place of Chrome Developer Tools, set the REACT_DEBUGGER environment variable to a command that will start your custom debugger. You can then select "Debug JS Remotely" from the Developer Menu to start debugging.

The debugger will receive a list of all project roots, separated by a space. For example, if you set REACT_DEBUGGER="node /path/to/launchDebugger.js --port 2345 --type ReactNative", then the command node /path/to/launchDebugger.js --port 2345 --type ReactNative /path/to/reactNative/app will be used to start your debugger.

Custom debugger commands executed this way should be short-lived processes, and they shouldn't produce more than 200 kilobytes of output.

React Developer Tools #

With React Native 0.43 or higher, you can use the standalone version of React Developer Tools to debug the React component hierarchy. To use it, install the react-devtools package globally:

npm install -g react-devtools

Now run react-devtools from the terminal to launch the standalone DevTools app:

react-devtools

React DevTools

It should connect to your simulator within a few seconds.

Note: if you prefer to avoid global installations, you can add react-devtools as a project dependency. With Yarn, you can run yarn add --dev react-devtools, and then run yarn react-devtools from your project folder to open the DevTools. With npm, you can run npm install --save-dev react-devtools, add "react-devtools": "react-devtools" to the scripts section in your package.json, and then run npm run react-devtools from your project folder to open the DevTools.

Integration with React Native Inspector #

You can open the in-app developer menu and choose "Show Inspector". It will bring up an overlay that lets you tap on any UI element and see information about it:

React Native Inspector

However, when react-devtools is running, Inspector will enter a special collapsed mode, and instead use the DevTools as primary UI. In this mode, clicking on something in the simulator will bring up the relevant components in the DevTools:

React DevTools Inspector Integration

You can choose "Hide Inspector" in the same menu to exit this mode.

Inspecting Component Instances #

When debugging JavaScript in Chrome, you can inspect the props and state of the React components in the browser console.

First, follow the instructions for debugging in Chrome to open the Chrome console.

Make sure that the dropdown in the top left corner of the Chrome console says debuggerWorker.js. This step is essential.

Then select a React component in React DevTools. There is a search box at the top that helps you find one by name. As soon as you select it, it will be available as $r in the Chrome console, letting you inspect its props, state, and instance properties.

React DevTools Chrome Console Integration

Performance Monitor #

You can enable a performance overlay to help you debug performance problems by selecting "Perf Monitor" in the Developer Menu.

Debugging in Ejected Apps #