Accessing console logs

Summary:
Instructions for accessing the output of a `console.log`.

![debugging](https://cloud.githubusercontent.com/assets/165856/16318119/7aff884e-3942-11e6-9a78-853aaba68308.png)
Closes #8323

Differential Revision: D3480718

Pulled By: JoelMarcey

fbshipit-source-id: 4185d2e730277b8ad986d3c8904420e7ae1ceb21

Author: hramos

docs/Debugging.md

@@ -9,30 +9,30 @@ next: testing
 
 ## 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.
+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.
 
 ![](img/DeveloperMenu.png)
 
 > The Developer Menu is disabled in release (production) builds.
 
 ## Reloading JavaScript
 
-Selecting `Reload` from the Developer Menu will reload the JavaScript that powers your application. You can also press `Command⌘ + R` in the iOS Simulator, or press `R` twice on Android emulators.
+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.
 
-> If you are using a Dvorak/Colemak layout, use the `Command⌘ + P` keyboard shortcut to reload the simulator.
+> If the **`Command`**`⌘` + **`R`** keyboard shortcut does not seem to reload the iOS Simulator, go to the Hardware menu, select Keyboard, and make sure that "Connect Hardware Keyboard" is checked.
 
-You will need to rebuild your app for changes to take effect in certain situations:
+### Automatic reloading
 
-* You have added new resources to your native app's bundle, such as an image in `Images.xcassets` on iOS or in `res/drawable` folder on Android.
-* You have modified native code (Objective-C/Swift on iOS or Java/C++ on Android).
+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.
 
-> If the `Command⌘ + R` keyboard shortcut does not seem to reload the iOS Simulator, go to the Hardware menu, select Keyboard, and make sure that "Connect Hardware Keyboard" is checked.
+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](https://facebook.github.io/react-native/blog/2016/03/24/introducing-hot-reloading.html) from the Developer Menu. This will allow you to persist the app's state through reloads.
 
-### Automatic reloading
+> 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 may enable Live Reload to automatically trigger a reload whenever your JavaScript code changes.
+You will need to rebuild your app for changes to take effect in certain situations:
 
-Live Reload is available on iOS via the Developer Menu. On Android, select "Dev Settings" from the Developer Menu and enable "Auto reload on JS change".
+* 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
 
@@ -52,41 +52,46 @@ YellowBoxes can be disabled during development by using `console.disableYellowBo
 
 > RedBoxes and YellowBoxes are automatically disabled in release (production) builds.
 
-## Accessing logs
+## Accessing console logs
 
-Run `react-native log-ios` in a terminal to display the logs for an iOS app running on a device or a simulator.
+You can display the console logs for an iOS or Android app by using the following commands in a terminal while the app is running:
 
-You can also view the iOS logs in Xcode: open your app in Xcode, then Build and Run your app on a device or the iPhone Simulator. The console should appear automatically after the app launches. If your app is failing to build, check the Issues Navigator in Xcode.
+```
+$ react-native log-ios
+$ react-native log-android
+```
 
-Run `react-native log-android` in a terminal to display the logs for an Android app running on a device or an emulator.
+You may also access these through `Debug → Open System Log...` in the iOS Simulator or by running `adb logcat *:S ReactNative:V ReactNativeJS:V` in a terminal while an Android app is running on a device or emulator.
 
 ## 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](http://localhost:8081/debugger-ui).
+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](http://localhost:8081/debugger-ui).
 
-In Chrome, press `Command⌘ + Option⌥ + I` or select `View` → `Developer` → `Developer Tools` to toggle the developer tools console. Enable [Pause On Caught Exceptions](http://stackoverflow.com/questions/2233339/javascript-is-there-a-way-to-get-chrome-to-break-on-all-errors/17324511#17324511) for a better debugging experience.
+Select `Tools → Developer Tools` from the Chrome Menu to open the [Developer Tools](https://developer.chrome.com/devtools). 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](http://stackoverflow.com/questions/2233339/javascript-is-there-a-way-to-get-chrome-to-break-on-all-errors/17324511#17324511) for a better debugging experience.
 
 > It is [currently not possible](https://github.com/facebook/react-devtools/issues/229) to use the "React" tab in the Chrome Developer Tools to inspect app widgets. You can use Nuclide's "React Native Inspector" as a workaround.
 
 ### Debugging on a device with Chrome Developer Tools
 
-On iOS devices, open the file [`RCTWebSocketExecutor.m`](https://github.com/facebook/react-native/blob/master/Libraries/WebSocket/RCTWebSocketExecutor.m) and change `localhost` to the IP address of your computer, then select `Debug JS Remotely` from the Developer Menu.
+On iOS devices, open the file [`RCTWebSocketExecutor.m`](https://github.com/facebook/react-native/blob/master/Libraries/WebSocket/RCTWebSocketExecutor.m) and change "localhost" to the IP address of your computer, then select "Debug JS Remotely" from the Developer Menu.
 
 On Android 5.0+ devices connected via USB, you can use the [`adb` command line tool](http://developer.android.com/tools/help/adb.html) to setup port forwarding from the device to your computer:
 
 `adb reverse tcp:8081 tcp:8081`
 
-Alternatively, select `Dev Settings` from the Developer Menu, then update the `Debug server host for device` setting to match the IP address of your computer.
+Alternatively, select "Dev Settings" from the Developer Menu, then update the "Debug server host for device" setting to match the IP address of your computer.
 
 > If you run into any issues, it may be possible that one of your Chrome extensions is interacting in unexpected ways with the debugger. Try disabling all of your extensions and re-enabling them one-by-one until you find the problematic extension.
 
 
 ### 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.
+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.
 
-> 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.
+> Custom debugger commands executed this way should be short-lived processes, and they shouldn't produce more than 200 kilobytes of output.
 
-## FPS (Frames per Second) Monitor
+## Performance Monitor
 
-You can enable a FPS graph overlay in the Developer Menu in order to help you debug performance problems.
+You can enable a performance overlay to help you debug performance problems by selecting "Perf Monitor" in the Developer Menu.