diff --git a/modules/openapi-generator/src/main/resources/Javascript/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Javascript/ApiClient.mustache
index d06606a38be..8182d519770 100644
--- a/modules/openapi-generator/src/main/resources/Javascript/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Javascript/ApiClient.mustache
@@ -306,16 +306,16 @@
     }
     switch (collectionFormat) {
       case 'csv':
-        return param.map(this.paramToString).join(',');
+        return param.map(this.paramToString, this).join(',');
       case 'ssv':
-        return param.map(this.paramToString).join(' ');
+        return param.map(this.paramToString, this).join(' ');
       case 'tsv':
-        return param.map(this.paramToString).join('\t');
+        return param.map(this.paramToString, this).join('\t');
       case 'pipes':
-        return param.map(this.paramToString).join('|');
+        return param.map(this.paramToString, this).join('|');
       case 'multi':
         // return the array directly as SuperAgent will handle it as expected
-        return param.map(this.paramToString);
+        return param.map(this.paramToString, this);
       default:
         throw new Error('Unknown collection format: ' + collectionFormat);
     }
diff --git a/modules/openapi-generator/src/main/resources/Javascript/es6/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Javascript/es6/ApiClient.mustache
index ff9799a1554..445073d5c01 100644
--- a/modules/openapi-generator/src/main/resources/Javascript/es6/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Javascript/es6/ApiClient.mustache
@@ -272,16 +272,16 @@ class ApiClient {
         }
         switch (collectionFormat) {
             case 'csv':
-                return param.map(this.paramToString).join(',');
+                return param.map(this.paramToString, this).join(',');
             case 'ssv':
-                return param.map(this.paramToString).join(' ');
+                return param.map(this.paramToString, this).join(' ');
             case 'tsv':
-                return param.map(this.paramToString).join('\t');
+                return param.map(this.paramToString, this).join('\t');
             case 'pipes':
-                return param.map(this.paramToString).join('|');
+                return param.map(this.paramToString, this).join('|');
             case 'multi':
                 //return the array directly as SuperAgent will handle it as expected
-                return param.map(this.paramToString);
+                return param.map(this.paramToString, this);
             default:
                 throw new Error('Unknown collection format: ' + collectionFormat);
         }
diff --git a/samples/client/petstore/javascript-es6/src/ApiClient.js b/samples/client/petstore/javascript-es6/src/ApiClient.js
index a6b7b871820..fa308c73adc 100644
--- a/samples/client/petstore/javascript-es6/src/ApiClient.js
+++ b/samples/client/petstore/javascript-es6/src/ApiClient.js
@@ -270,16 +270,16 @@ class ApiClient {
         }
         switch (collectionFormat) {
             case 'csv':
-                return param.map(this.paramToString).join(',');
+                return param.map(this.paramToString, this).join(',');
             case 'ssv':
-                return param.map(this.paramToString).join(' ');
+                return param.map(this.paramToString, this).join(' ');
             case 'tsv':
-                return param.map(this.paramToString).join('\t');
+                return param.map(this.paramToString, this).join('\t');
             case 'pipes':
-                return param.map(this.paramToString).join('|');
+                return param.map(this.paramToString, this).join('|');
             case 'multi':
                 //return the array directly as SuperAgent will handle it as expected
-                return param.map(this.paramToString);
+                return param.map(this.paramToString, this);
             default:
                 throw new Error('Unknown collection format: ' + collectionFormat);
         }
diff --git a/samples/client/petstore/javascript-promise-es6/src/ApiClient.js b/samples/client/petstore/javascript-promise-es6/src/ApiClient.js
index ead1a81b942..cd449f850c4 100644
--- a/samples/client/petstore/javascript-promise-es6/src/ApiClient.js
+++ b/samples/client/petstore/javascript-promise-es6/src/ApiClient.js
@@ -270,16 +270,16 @@ class ApiClient {
         }
         switch (collectionFormat) {
             case 'csv':
-                return param.map(this.paramToString).join(',');
+                return param.map(this.paramToString, this).join(',');
             case 'ssv':
-                return param.map(this.paramToString).join(' ');
+                return param.map(this.paramToString, this).join(' ');
             case 'tsv':
-                return param.map(this.paramToString).join('\t');
+                return param.map(this.paramToString, this).join('\t');
             case 'pipes':
-                return param.map(this.paramToString).join('|');
+                return param.map(this.paramToString, this).join('|');
             case 'multi':
                 //return the array directly as SuperAgent will handle it as expected
-                return param.map(this.paramToString);
+                return param.map(this.paramToString, this);
             default:
                 throw new Error('Unknown collection format: ' + collectionFormat);
         }