add helper function to encode and decode unicode strings

Author: Xnaff

readme.md

@@ -82,6 +82,8 @@ This plugin allows you to interact with Bluetooth LE devices on Android, iOS, an
   - [bytesToEncodedString](#bytestoencodedstring)
   - [stringToBytes](#stringtobytes)
   - [bytesToString](#bytestostring)
+  - [encodeUnicode](#encodeunicode)
+  - [decodeUnicode](#decodeunicode)
 - [Example](#example)
 - [Data Parsing Example](#data-parsing-example)
 - [Sample: Discover and interact with Bluetooth LE devices](#sample-discover-and-interact-with-bluetooth-le-devices)
@@ -254,6 +256,8 @@ Neither Android nor iOS support Bluetooth on emulators, so you'll need to test o
 * [bluetoothle.bytesToEncodedString](#bytestoencodedstring)
 * [bluetoothle.stringToBytes](#stringtobytes)
 * [bluetoothle.bytesToString](#bytestostring)
+* [bluetoothle.encodeUnicode](#encodeunicode)
+* [bluetoothle.decodeUnicode](#decodeunicode)
 
 
 
@@ -1271,6 +1275,8 @@ To write without response, set type to "noResponse". Any other value will defaul
 var string = "Write Hello World";
 var bytes = bluetoothle.stringToBytes(string);
 var encodedString = bluetoothle.bytesToEncodedString(bytes);
+// if your code includes special characters you should use the encodeUnicode helper function
+var encodedUnicodeString = bluetoothle.encodeUnicode(string);
 
 //Note, this example doesn't actually work since it's read only characteristic
 {"value":"V3JpdGUgSGVsbG8gV29ybGQ=","service":"180F","characteristic":"2A19","type":"noResponse","address":"ABC123"}
@@ -1283,6 +1289,9 @@ Value is a base64 encoded string of written bytes. Use bluetoothle.encodedString
 var returnObj = {"status":"written","service":"180F","characteristic":"2A19","value":"V3JpdGUgSGVsbG8gV29ybGQ=","address":"ABC123"}
 var bytes = bluetoothle.encodedStringToBytes(returnObj.value);
 var string = bluetoothle.bytesToString(bytes); //This should equal Write Hello World
+
+// if your code includes special characters you should use the decodeUnicode helper function
+var string = bluetoothle.decodeUnicode(returnObj.value);
 ```
 
 
@@ -2243,6 +2252,20 @@ if (obj.status == "subscribedResult")
 }
 ```
 
+### encodeUnicode ###
+Helper function to convert unicode string to base64 encoded string. This function can be used to encode special characters such as emojis.
+
+```javascript
+bluetoothle.encodeUnicode(string);
+```
+
+### decodeUnicode ###
+Helper function to convert a base64 encoded string to unicode string. This function also decodes special characters such as emojis.
+
+```javascript
+bluetoothle.decodeUnicode(string);
+```
+
 ## Sample: Discover and interact with Bluetooth LE devices ##
 
 We'll build an app that lets you discover Bluetooth Low Energy (LE) devices that are around you, connect to a one, and then look at all of the information that you can obtain from that device such as signal strength, supported services, battery level and more.

types/index.d.ts

@@ -592,6 +592,20 @@ declare namespace BluetoothlePlugin {
          * @return          Encoded string
          */
         bytesToString(value: Uint8Array): string;
+
+        /**
+         * Helper function to convert string to base64.
+         * @param  value    string
+         * @return          base64 string
+         */
+        encodeUnicode(value: string): string;
+
+        /**
+         * Helper function to convert bytes to a string.
+         * @param  value    base64 string
+         * @return          string
+         */
+        decodeUnicode(value: string): string;
     }
 
     /* Available status of device */

www/bluetoothle.js

@@ -170,6 +170,17 @@ var bluetoothle = {
   bytesToString: function(bytes) {
     return String.fromCharCode.apply(null, new Uint16Array(bytes));
   },
+  encodeUnicode: function(str) {
+    return btoa(encodeURIComponent(str).replace(/%([0-9A-F]{2})/g, (match, p1) => {
+      return String.fromCharCode(parseInt(p1, 16))
+    }))
+  },
+  decodeUnicode: function(str) {
+    // Going backwards: from byte stream, to percent-encoding, to original string.
+    return decodeURIComponent(atob(str).split('').map((c) => {
+      return '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2);
+    }).join(''));
+  },
   bytesToHex: function(bytes) {
     var string = [];
     for (var i = 0; i < bytes.length; i++) {