add example

index.js

@@ -0,0 +1,19 @@
+const DevObj = require('./deviceObject')
+
+;(async function () {
+
+  let list = await DevObj.getPorts()
+  console.log('get port list :::: ', list)
+
+  let dev = new DevObj('/dev/tty.SLAB_USBtoUART', null)
+  dev.on('open', () => {
+    console.log('dev open')
+  }).on('close', () => {
+    console.log('dev close')
+  })
+
+  dev.connect()
+
+}()).then(() => {}).catch(err => {
+  console.log(err)
+})