fix bug and add service file

1.修正列印大小無法寫入BUG
2.加入SYSTEMD系統服務腳本

PrinterDev.js

@@ -66,7 +66,7 @@ class PrinterDevice {
           case 's':
             let size = tmp.substring(2)
             let sarr = size.trim().split(',')
-            if (sarr != 2) break
+            if (sarr.length != 2) break
             if(!isFinite(sarr[0]) || !isFinite(sarr[1])) break
             sarr = sarr.map(t => Math.floor(t))
             this._printer.size(sarr[0], sarr[1])

initscript/systemd/ble-server.service

@@ -0,0 +1,11 @@
+[Unit]
+Description=BLE Printer Server
+
+[Service]
+ExecStart=/usr/bin/node /usr/local/node/ble-server/app.js
+Restart=always
+User=root
+Environment="NODE_ENV=production"
+
+[Install]
+WantedBy=multi-user.target