Created Module Debugging (markdown)

Module-Debugging.md

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+### How to debug your module while in development?
+
+As it can take several seconds and even minutes to restart your MM, it may be a bottleneck for development efficiency. Here are a (very) few suggestions to help debug your MM Module while under development. 
+
+There are at least 2-3 ways to [test modules](https://forum.magicmirror.builders/topic/86/how-to-troubleshoot/7):
+
+1. Directly on MM itself (native mode)
+2. Directly on MM itself (server mode)
+3. As a node server or on a different machine [TBA]
+
+----
+
+#### General Debug Tips
+
+* Run your MM in *server mode*, so that you still can use your RPi (or what have) in GUI mode, this also reduces it's CPU resources somewhat. 
+* Disable all other modules (except clock) to make it start/run faster and to isolate your Dev Module
+* Use your browsers' `Developer Tools` (usually activated by `CTRL-SHIFT-i`) to check/debug JS etc.
+* Check your JS code with some external site, like [jslint](http://jslint.com/)
+* Check your JS code with some GUI (*Visual Studio*?) or command line utility... [TBA]
+* Check your PM2 logs with `pm2 logs mm` or check the log files in their locations:
+
+  - `/home/pi/.pm2/pm2.log`
+  - `/home/pi/.pm2/logs/mm-error-0.log`
+  - `/home/pi/.pm2/logs/mm-out-0.log`
+
+* Finally, and most useful, check the entire *npm* configuration with: `npm run config:check`
+
+```bash
+cd ~/MagicMirror/
+npm run config:check
+```
+
+There are probably many other and better ways to check and debug. So please add and edit this page or file an issue with info for improving debugging.