Improve documentation, remove incorrect statement, only use options f…

…or check

src/Auth0Client.ts

@@ -209,7 +209,6 @@ export class Auth0Client {
   private readonly isAuthenticatedCookieName: string;
   private readonly nowProvider: () => number | Promise<number>;
   private readonly httpTimeoutMs: number;
-  private readonly useRefreshTokensFallback: boolean;
 
   cacheLocation: CacheLocation;
   private worker: Worker;
@@ -307,9 +306,6 @@ export class Auth0Client {
     }
 
     this.customOptions = getCustomInitialOptions(options);
-
-    this.useRefreshTokensFallback =
-      this.options.useRefreshTokensFallback === true;
   }
 
   private _url(path: string) {
@@ -817,7 +813,7 @@ export class Auth0Client {
    * remaining before expiration, return the token. Otherwise, attempt
    * to obtain a new token.
    *
-   * A new token will be obtained either by opening an iframe (if `useRefreshTokensFallback` is true) or a
+   * A new token will be obtained either by opening an iframe or a
    * refresh token (if `useRefreshTokens` is `true`).
 
    * If iframes are used, opens an iframe with the `/authorize` URL
@@ -829,7 +825,7 @@ export class Auth0Client {
    * 'refresh_token' grant. If no refresh token is available to make this call,
    * the SDK will only fall back to using an iframe to the '/authorize' URL if 
    * the `useRefreshTokensFallback` setting has been set to `true`. By default this
-   * setting is false.
+   * setting is `false`.
    *
    * This method may use a web worker to perform the token call if the in-memory
    * cache is used.
@@ -1193,7 +1189,7 @@ export class Auth0Client {
     // and useRefreshTokensFallback was explicitly enabled
     // fallback to an iframe
     if ((!cache || !cache.refresh_token) && !this.worker) {
-      if (this.useRefreshTokensFallback) {
+      if (this.options.useRefreshTokensFallback) {
         return await this._getTokenFromIFrame(options);
       }
 
@@ -1252,7 +1248,7 @@ export class Auth0Client {
           // and useRefreshTokensFallback is explicitly enabled. Fallback to an iframe.
           (e.message &&
             e.message.indexOf(INVALID_REFRESH_TOKEN_ERROR_MESSAGE) > -1)) &&
-        this.useRefreshTokensFallback
+        this.options.useRefreshTokensFallback
       ) {
         return await this._getTokenFromIFrame(options);
       }

src/global.ts

@@ -160,11 +160,11 @@ export interface Auth0ClientOptions extends BaseLoginOptions {
 
   /**
    * If true, fallback to the technique of using a hidden iframe and the `authorization_code` grant with `prompt=none` when unable to use refresh tokens. If false, the iframe fallback is not used and
-   * errors relating to a failed Refresh Grant should be handled appropriately by having the user to login. The default setting is `false`.
+   * errors relating to a failed `refresh_token` grant should be handled appropriately. The default setting is `false`.
    *
    * **Note**: There might be situations where doing silent auth with a Web Message response from an iframe is not possible,
    * like when you're serving your application from the file system or a custom protocol (like in a Desktop or Native app).
-   * In situations like this you can disable the iframe fallback and handle the failed Refresh Grant and prompt the user to login interactively with `loginWithRedirect` or `loginWithPopup`."
+   * In situations like this you can disable the iframe fallback and handle the failed `refresh_token` grant and prompt the user to login interactively with `loginWithRedirect` or `loginWithPopup`."
    *
    * E.g. Using the `file:` protocol in an Electron application does not support that legacy technique.
    *