Merge pull request #158 from haraldkubota/master

Add Node.js program to scan for reflashed LYWSD03MMC

contrib/nodejs/.gitignore

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+node_modules/
+

contrib/nodejs/README.md

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+# Scan for reflashed LYWSD03MMC
+
+This short Node.js program scans for BLE announcements from the reflashed LYWSD03MMC 
+Mijia Thermometer+Hygrometer from https://github.com/atc1441/ATC_MiThermometer
+
+## Usage
+
+```
+❯ npm install
+[...]
+❯ node scan-thermometer.js
+Sat Jan 09 2021 12:27:49 GMT+0900 (Japan Standard Time) ATC_C1CADA T=24.4, H=35% Batt=100%
+```
+The program terminates after 60s
+
+### Options
+
+```
+❯ node scan-thermometer.js -h
+Usage: scan-thermometer [options]
+
+Options:
+  -d, --debug             extra debugging
+  -t, --timeout <value>   timeout in seconds
+  -a, --allow-duplicates  show duplicate device discoveries
+  -u, --uuids             Show all UUIDs (default: only 181a)
+  -h, --help              display help for command
+```
+
+### Notes
+
+Sometimes the device name is not defined (shows as "undefined" instead of "ATC_C1CADA" in above example), but if duplicates are not allowed, it'll not show up again with its correct name. Using "--allow-duplicates" will usually show the correct device name at the 2nd message and any subsequent received message.
+
+node needs to have permission to to raw connecta to the network, so either use sudo:
+```
+❯ sudo node scan-thermometer.js
+```
+or set capabilities for the node binary to allow raw connects to the network:
+```
+❯ sudo setcap cap_net_raw+eip $(eval readlink -f `which node`)
+```
+and then you don't need sudo anymore.