add: TOTP.now function

src/totp.js

@@ -4,6 +4,7 @@
  */
 
 import { OTP } from './otp';
+import { Util } from './util';
 
 export class TOTP extends OTP {
     /*＊
@@ -35,7 +36,12 @@ export class TOTP extends OTP {
      * ```
      */
     now() {
-        return "TOTP.now";
+        // get now time string
+        let now = Util.timecode(new Date(), this.interval);
+
+        // generate the one-time password
+        let digit = super.generate_otp(now);
+        return digit;
     }
 
     /*＊

test/totp_test.js

@@ -4,11 +4,11 @@ var assert = require('assert');
 describe('TOTP module test', function() {
 
     var TOTP = totp.TOTP;
-    var a = new TOTP("BASE32_ENCODED_SECRET");
+    var a = new TOTP("J22U6B3WIWRRBTAV");
     
     describe('now() function', function() {
         it("should print 'TOTP.now'", function() {
-            assert.equal("TOTP.now", a.now());
+            assert.equal("string", typeof(a.now()));
         });
     });