Add backend README - Backend watchers setup

backend/README.md

@@ -0,0 +1,33 @@
+# Setup backend watchers
+
+The backend is static. Typescript scripts are compiled into the `dist` folder and served through a node web server.
+
+You can avoid the manual shutdown/recompile/restart command line cycle by setting up watchers.
+
+Make sure you are in the `backend` directory `cd backend`.
+
+1. Install nodemon 
+```
+sudo npm install -g nodemon
+```
+2. [Optional] Add the following configuration into `tsconfig.json`. You can find watch options here https://www.typescriptlang.org/docs/handbook/configuring-watch.html
+```
+    "watchOptions": {
+      "watchFile": "useFsEvents",
+      "watchDirectory": "useFsEvents",
+      "fallbackPolling": "dynamicPriority",
+      "synchronousWatchDirectory": true,
+      "excludeDirectories": ["**/node_modules", "_build"],
+      "excludeFiles": ["build/fileWhichChangesOften.ts"]
+    }
+```
+3. In one terminal, watch typescript scripts
+```
+./node_modules/typescript/bin/tsc --watch
+```
+4. In another terminal, watch compiled javascript
+```
+nodemon --max-old-space-size=2048 dist/index.js
+```
+
+Everytime you save a backend `.ts` file, `tsc` will recompile it and genereate a new static `.js` file in the `dist` folder. `nodemon` will detect this new file and restart the node web server automatically.