updated JavaScript utils file to include new methods.

created a unified flow to be an example.

www/BluememeUtils.js

@@ -1,11 +1,21 @@
 'use strict';
 
 var exec = require('cordova/exec');
+
 var SERVICE = 'BluememeUtils';
-var eventHandlers = {};
+var EVENT_PREFIX = 'bluememeutils.';
+var eventHandlers = Object.create(null);
 
 function noop() {}
 
+function isFunction(value) {
+    return typeof value === 'function';
+}
+
+function callbackOrNoop(callback) {
+    return isFunction(callback) ? callback : noop;
+}
+
 function asWifiOptions(input) {
     if (typeof input === 'string') {
         return { ssid: input };
@@ -14,11 +24,35 @@ function asWifiOptions(input) {
 }
 
 function call(action, args, success, error) {
-    exec(success || noop, error || noop, SERVICE, action, args || []);
+    exec(callbackOrNoop(success), callbackOrNoop(error), SERVICE, action, args || []);
+}
+
+function noArgs(action) {
+    return function (success, error) {
+        call(action, [], success, error);
+    };
+}
+
+function oneArg(action, normalize) {
+    return function (value, success, error) {
+        call(action, [normalize ? normalize(value) : value], success, error);
+    };
+}
+
+function isPermissionGranted(permission) {
+    return !!permission && (permission.enabled === true || permission.granted === true);
+}
+
+function permissionError(type, permission) {
+    return {
+        code: 'PERMISSION_REQUIRED',
+        message: type + ' permission is required.',
+        permission: permission || null
+    };
 }
 
 function createCustomEvent(name, detail) {
-    var eventName = 'bluememeutils.' + name;
+    var eventName = EVENT_PREFIX + name;
 
     if (typeof window.CustomEvent === 'function') {
         return new window.CustomEvent(eventName, { detail: detail });
@@ -36,7 +70,13 @@ function dispatchLocalEvent(event) {
 
     var handlers = eventHandlers[event.type] || [];
     handlers.slice().forEach(function (handler) {
-        handler(event);
+        try {
+            handler(event);
+        } catch (ex) {
+            setTimeout(function () {
+                throw ex;
+            }, 0);
+        }
     });
 
     if (typeof window !== 'undefined' && typeof window.dispatchEvent === 'function') {
@@ -44,50 +84,70 @@ function dispatchLocalEvent(event) {
     }
 }
 
+function ensurePushPermission(success, error) {
+    var onSuccess = callbackOrNoop(success);
+    var onError = callbackOrNoop(error);
+
+    api.getPushPermissionStatus(function (status) {
+        if (isPermissionGranted(status)) {
+            onSuccess(status);
+            return;
+        }
+
+        api.requestPushPermission(function () {
+            api.getPushPermissionStatus(function (updatedStatus) {
+                if (isPermissionGranted(updatedStatus)) {
+                    onSuccess(updatedStatus);
+                    return;
+                }
+                onError(permissionError('notification', updatedStatus));
+            }, onError);
+        }, onError);
+    }, onError);
+}
+
+function getFirebaseTokenWithPermission(success, error) {
+    var onSuccess = callbackOrNoop(success);
+    var onError = callbackOrNoop(error);
+
+    ensurePushPermission(function (permission) {
+        api.getFirebaseToken(function (result) {
+            if (result && typeof result === 'object') {
+                result.permission = permission;
+            }
+            onSuccess(result);
+        }, onError);
+    }, onError);
+}
+
 var api = {
-    getDeviceInfo: function (success, error) {
-        call('getDeviceInfo', [], success, error);
-    },
+    getDeviceInfo: noArgs('getDeviceInfo'),
 
-    saveWifi: function (options, success, error) {
-        call('saveWifi', [asWifiOptions(options)], success, error);
-    },
+    saveWifi: oneArg('saveWifi', asWifiOptions),
 
-    connectWifi: function (options, success, error) {
-        call('connectWifi', [asWifiOptions(options)], success, error);
-    },
+    connectWifi: oneArg('connectWifi', asWifiOptions),
 
-    disconnectWifi: function (success, error) {
-        call('disconnectWifi', [], success, error);
-    },
+    disconnectWifi: noArgs('disconnectWifi'),
 
-    removeWifi: function (options, success, error) {
-        call('removeWifi', [asWifiOptions(options)], success, error);
-    },
+    removeWifi: oneArg('removeWifi', asWifiOptions),
 
-    requestWifiPermission: function (success, error) {
-        call('requestWifiPermission', [], success, error);
-    },
+    requestWifiPermission: noArgs('requestWifiPermission'),
 
-    isBiometricAvailable: function (success, error) {
-        call('isBiometricAvailable', [], success, error);
-    },
+    isBiometricAvailable: noArgs('isBiometricAvailable'),
 
-    unlockWithBiometrics: function (options, success, error) {
-        call('unlockWithBiometrics', [options || {}], success, error);
-    },
+    unlockWithBiometrics: oneArg('unlockWithBiometrics', function (options) {
+        return options || {};
+    }),
 
-    requestPushPermission: function (success, error) {
-        call('requestPushPermission', [], success, error);
-    },
+    requestPushPermission: noArgs('requestPushPermission'),
 
-    getPushPermissionStatus: function (success, error) {
-        call('getPushPermissionStatus', [], success, error);
-    },
+    getPushPermissionStatus: noArgs('getPushPermissionStatus'),
 
-    getFirebaseToken: function (success, error) {
-        call('getFirebaseToken', [], success, error);
-    },
+    ensurePushPermission: ensurePushPermission,
+
+    getFirebaseToken: noArgs('getFirebaseToken'),
+
+    getFirebaseTokenWithPermission: getFirebaseTokenWithPermission,
 
     subscribeToTopic: function (topic, success, error) {
         call('subscribeToTopic', [topic], success, error);
@@ -97,9 +157,7 @@ var api = {
         call('unsubscribeFromTopic', [topic], success, error);
     },
 
-    getInitialNotification: function (success, error) {
-        call('getInitialNotification', [], success, error);
-    },
+    getInitialNotification: noArgs('getInitialNotification'),
 
     startNotificationListener: function (success, error) {
         call('startNotificationListener', [], function (event) {
@@ -110,15 +168,19 @@ var api = {
         }, error);
     },
 
-    stopNotificationListener: function (success, error) {
-        call('stopNotificationListener', [], success, error);
-    },
+    stopNotificationListener: noArgs('stopNotificationListener'),
 
     on: function (type, handler) {
+        if (!isFunction(handler)) {
+            return noop;
+        }
         if (!eventHandlers[type]) {
             eventHandlers[type] = [];
         }
         eventHandlers[type].push(handler);
+        return function () {
+            api.off(type, handler);
+        };
     },
 
     off: function (type, handler) {