diff --git a/modules/openapi-generator/src/main/resources/Javascript/partial_model_generic.mustache b/modules/openapi-generator/src/main/resources/Javascript/partial_model_generic.mustache
index facd6bf222e..20b83c83782 100644
--- a/modules/openapi-generator/src/main/resources/Javascript/partial_model_generic.mustache
+++ b/modules/openapi-generator/src/main/resources/Javascript/partial_model_generic.mustache
@@ -26,7 +26,8 @@ class {{classname}} {{#parent}}{{^parentModel}}{{#vendorExtensions.x-is-array}}e
      * Only for internal use.
      */{{/emitJSDoc}}
     static initialize(obj{{#vendorExtensions.x-all-required}}, {{name}}{{/vendorExtensions.x-all-required}}) { {{#vars}}{{#required}}
-        {{#defaultValue}}obj['{{baseName}}'] = {{name}} || {{{defaultValue}}};{{/defaultValue}}{{^defaultValue}}obj['{{baseName}}'] = {{name}};{{/defaultValue}}{{/required}}{{/vars}}
+        {{#defaultValue}}obj['{{baseName}}'] = {{name}} || {{{defaultValue}}};{{/defaultValue}}{{^defaultValue}}obj['{{baseName}}'] = {{name}};{{/defaultValue}}{{/required}}{{#defaultValue}}{{^required}}
+        obj['{{baseName}}'] = {{{defaultValue}}};{{/required}}{{/defaultValue}}{{/vars}}
     }
 
     {{#emitJSDoc}}/**
diff --git a/samples/client/petstore/javascript-apollo/src/model/Animal.js b/samples/client/petstore/javascript-apollo/src/model/Animal.js
index f9180d4520f..f780272847e 100644
--- a/samples/client/petstore/javascript-apollo/src/model/Animal.js
+++ b/samples/client/petstore/javascript-apollo/src/model/Animal.js
@@ -36,6 +36,7 @@ class Animal {
      */
     static initialize(obj, className) { 
         obj['className'] = className;
+        obj['color'] = 'red';
     }
 
     /**
diff --git a/samples/client/petstore/javascript-apollo/src/model/Foo.js b/samples/client/petstore/javascript-apollo/src/model/Foo.js
index 3fc7819f99f..e808b774ec0 100644
--- a/samples/client/petstore/javascript-apollo/src/model/Foo.js
+++ b/samples/client/petstore/javascript-apollo/src/model/Foo.js
@@ -34,6 +34,7 @@ class Foo {
      * Only for internal use.
      */
     static initialize(obj) { 
+        obj['bar'] = 'bar';
     }
 
     /**
diff --git a/samples/client/petstore/javascript-apollo/src/model/Order.js b/samples/client/petstore/javascript-apollo/src/model/Order.js
index ad586f185d4..0568b473315 100644
--- a/samples/client/petstore/javascript-apollo/src/model/Order.js
+++ b/samples/client/petstore/javascript-apollo/src/model/Order.js
@@ -34,6 +34,7 @@ class Order {
      * Only for internal use.
      */
     static initialize(obj) { 
+        obj['complete'] = false;
     }
 
     /**
diff --git a/samples/client/petstore/javascript-es6/src/model/Animal.js b/samples/client/petstore/javascript-es6/src/model/Animal.js
index f9180d4520f..f780272847e 100644
--- a/samples/client/petstore/javascript-es6/src/model/Animal.js
+++ b/samples/client/petstore/javascript-es6/src/model/Animal.js
@@ -36,6 +36,7 @@ class Animal {
      */
     static initialize(obj, className) { 
         obj['className'] = className;
+        obj['color'] = 'red';
     }
 
     /**
diff --git a/samples/client/petstore/javascript-es6/src/model/Foo.js b/samples/client/petstore/javascript-es6/src/model/Foo.js
index 3fc7819f99f..e808b774ec0 100644
--- a/samples/client/petstore/javascript-es6/src/model/Foo.js
+++ b/samples/client/petstore/javascript-es6/src/model/Foo.js
@@ -34,6 +34,7 @@ class Foo {
      * Only for internal use.
      */
     static initialize(obj) { 
+        obj['bar'] = 'bar';
     }
 
     /**
diff --git a/samples/client/petstore/javascript-es6/src/model/Order.js b/samples/client/petstore/javascript-es6/src/model/Order.js
index ad586f185d4..0568b473315 100644
--- a/samples/client/petstore/javascript-es6/src/model/Order.js
+++ b/samples/client/petstore/javascript-es6/src/model/Order.js
@@ -34,6 +34,7 @@ class Order {
      * Only for internal use.
      */
     static initialize(obj) { 
+        obj['complete'] = false;
     }
 
     /**
diff --git a/samples/client/petstore/javascript-promise-es6/src/model/Animal.js b/samples/client/petstore/javascript-promise-es6/src/model/Animal.js
index f9180d4520f..f780272847e 100644
--- a/samples/client/petstore/javascript-promise-es6/src/model/Animal.js
+++ b/samples/client/petstore/javascript-promise-es6/src/model/Animal.js
@@ -36,6 +36,7 @@ class Animal {
      */
     static initialize(obj, className) { 
         obj['className'] = className;
+        obj['color'] = 'red';
     }
 
     /**
diff --git a/samples/client/petstore/javascript-promise-es6/src/model/Foo.js b/samples/client/petstore/javascript-promise-es6/src/model/Foo.js
index 3fc7819f99f..e808b774ec0 100644
--- a/samples/client/petstore/javascript-promise-es6/src/model/Foo.js
+++ b/samples/client/petstore/javascript-promise-es6/src/model/Foo.js
@@ -34,6 +34,7 @@ class Foo {
      * Only for internal use.
      */
     static initialize(obj) { 
+        obj['bar'] = 'bar';
     }
 
     /**
diff --git a/samples/client/petstore/javascript-promise-es6/src/model/Order.js b/samples/client/petstore/javascript-promise-es6/src/model/Order.js
index ad586f185d4..0568b473315 100644
--- a/samples/client/petstore/javascript-promise-es6/src/model/Order.js
+++ b/samples/client/petstore/javascript-promise-es6/src/model/Order.js
@@ -34,6 +34,7 @@ class Order {
      * Only for internal use.
      */
     static initialize(obj) { 
+        obj['complete'] = false;
     }
 
     /**