Promisified: add checking of existing of Promise API

src/users/social/facebook.js

@@ -1,4 +1,5 @@
 import Async from '../../request/async'
+import Utils from '../../utils'
 
 import { loginSocial } from './login'
 import { sendSocialLoginRequest } from './request'
@@ -8,6 +9,8 @@ export const loginWithFacebook = (fieldsMapping, permissions, stayLoggedIn, asyn
 }
 
 export const loginWithFacebookSdk = (fieldsMapping, stayLoggedIn, options) => {
+  Utils.checkPromiseSupport()
+
   return new Promise((resolve, reject) => {
     if (!FB) {
       return reject(new Error('Facebook SDK not found'))

src/users/social/google.js

@@ -1,4 +1,5 @@
 import Async from '../../request/async'
+import Utils from '../../utils'
 
 import { loginSocial } from './login'
 import { sendSocialLoginRequest } from './request'
@@ -8,6 +9,8 @@ export const loginWithGooglePlus = (fieldsMapping, permissions, container, stayL
 }
 
 export const loginWithGooglePlusSdk = (fieldsMapping, stayLoggedIn) => {
+  Utils.checkPromiseSupport()
+
   return new Promise((resolve, reject) => {
     if (!gapi) {
       return reject(new Error('Google Plus SDK not found'))

src/utils.js

@@ -150,6 +150,8 @@ const Utils = {
 
   promisified(method) {
     return function() {
+      Utils.checkPromiseSupport()
+
       const args = [].slice.call(arguments)
       const context = this
       const fn = typeof method === 'function' ? method : context[method]
@@ -170,6 +172,15 @@ const Utils = {
 
       return fn.apply(context, arguments)
     }
+  },
+
+  checkPromiseSupport() {
+    if (typeof Promise === 'undefined') {
+      throw new Error(
+        'This browser doesn\'t support Promise API. Please use polyfill.\n' +
+        'More info is in the Backendless JS-SDK docs: https://backendless.com/docs/js/doc.html#sync-and-async-calls'
+      )
+    }
   }
 }