diff --git a/.gitignore b/.gitignore
index 80fe14273..ae7aa58ad 100644
--- a/.gitignore
+++ b/.gitignore
@@ -126,3 +126,4 @@ Cargo.lock
 grpc/google/
 **/Package.resolved
 .clangd/**
+package-lock.json
diff --git a/src/idl_gen_js_ts.cpp b/src/idl_gen_js_ts.cpp
index b09de5a5e..ad1d8a0c2 100644
--- a/src/idl_gen_js_ts.cpp
+++ b/src/idl_gen_js_ts.cpp
@@ -1625,19 +1625,25 @@ class JsTsGenerator : public BaseGenerator {
                   " = function(value) {\n";
         }
 
-        code += "  var offset = " + GenBBAccess() + ".__offset(this.bb_pos, " +
-                NumToString(field.value.offset) + ");\n\n";
-        code += "  if (offset === 0) {\n";
-        code += "    return false;\n";
-        code += "  }\n\n";
+        if (struct_def.fixed) {
+          code += "  " + GenBBAccess() + ".write" +
+                  MakeCamel(GenType(field.value.type)) +
+                  "(this.bb_pos + " + NumToString(field.value.offset) + ", ";
+        } else {
+          code += "  var offset = " + GenBBAccess() + ".__offset(this.bb_pos, " +
+                  NumToString(field.value.offset) + ");\n\n";
+          code += "  if (offset === 0) {\n";
+          code += "    return false;\n";
+          code += "  }\n\n";
 
-        // special case for bools, which are treated as uint8
-        code += "  " + GenBBAccess() + ".write" +
-                MakeCamel(GenType(field.value.type)) +
-                "(this.bb_pos + offset, ";
-        if (field.value.type.base_type == BASE_TYPE_BOOL &&
-            lang_.language == IDLOptions::kTs) {
-          code += "+";
+          // special case for bools, which are treated as uint8
+          code += "  " + GenBBAccess() + ".write" +
+                  MakeCamel(GenType(field.value.type)) +
+                  "(this.bb_pos + offset, ";
+          if (field.value.type.base_type == BASE_TYPE_BOOL &&
+              lang_.language == IDLOptions::kTs) {
+            code += "+";
+          }
         }
 
         code += "value);\n";
diff --git a/tests/monster_test_generated.js b/tests/monster_test_generated.js
index 7339a7340..fedc2c0e1 100644
--- a/tests/monster_test_generated.js
+++ b/tests/monster_test_generated.js
@@ -322,13 +322,7 @@ MyGame.Example.Test.prototype.a = function() {
  * @returns {boolean}
  */
 MyGame.Example.Test.prototype.mutate_a = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 0);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeInt16(this.bb_pos + offset, value);
+  this.bb.writeInt16(this.bb_pos + 0, value);
   return true;
 };
 
@@ -344,13 +338,7 @@ MyGame.Example.Test.prototype.b = function() {
  * @returns {boolean}
  */
 MyGame.Example.Test.prototype.mutate_b = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 2);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeInt8(this.bb_pos + offset, value);
+  this.bb.writeInt8(this.bb_pos + 2, value);
   return true;
 };
 
@@ -509,13 +497,7 @@ MyGame.Example.Vec3.prototype.x = function() {
  * @returns {boolean}
  */
 MyGame.Example.Vec3.prototype.mutate_x = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 0);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeFloat32(this.bb_pos + offset, value);
+  this.bb.writeFloat32(this.bb_pos + 0, value);
   return true;
 };
 
@@ -531,13 +513,7 @@ MyGame.Example.Vec3.prototype.y = function() {
  * @returns {boolean}
  */
 MyGame.Example.Vec3.prototype.mutate_y = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 4);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeFloat32(this.bb_pos + offset, value);
+  this.bb.writeFloat32(this.bb_pos + 4, value);
   return true;
 };
 
@@ -553,13 +529,7 @@ MyGame.Example.Vec3.prototype.z = function() {
  * @returns {boolean}
  */
 MyGame.Example.Vec3.prototype.mutate_z = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 8);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeFloat32(this.bb_pos + offset, value);
+  this.bb.writeFloat32(this.bb_pos + 8, value);
   return true;
 };
 
@@ -575,13 +545,7 @@ MyGame.Example.Vec3.prototype.test1 = function() {
  * @returns {boolean}
  */
 MyGame.Example.Vec3.prototype.mutate_test1 = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 16);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeFloat64(this.bb_pos + offset, value);
+  this.bb.writeFloat64(this.bb_pos + 16, value);
   return true;
 };
 
@@ -597,13 +561,7 @@ MyGame.Example.Vec3.prototype.test2 = function() {
  * @returns {boolean}
  */
 MyGame.Example.Vec3.prototype.mutate_test2 = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 24);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeUint8(this.bb_pos + offset, value);
+  this.bb.writeUint8(this.bb_pos + 24, value);
   return true;
 };
 
@@ -681,13 +639,7 @@ MyGame.Example.Ability.prototype.id = function() {
  * @returns {boolean}
  */
 MyGame.Example.Ability.prototype.mutate_id = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 0);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeUint32(this.bb_pos + offset, value);
+  this.bb.writeUint32(this.bb_pos + 0, value);
   return true;
 };
 
@@ -703,13 +655,7 @@ MyGame.Example.Ability.prototype.distance = function() {
  * @returns {boolean}
  */
 MyGame.Example.Ability.prototype.mutate_distance = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 4);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeUint32(this.bb_pos + offset, value);
+  this.bb.writeUint32(this.bb_pos + 4, value);
   return true;
 };
 
diff --git a/tests/monster_test_generated.ts b/tests/monster_test_generated.ts
index b9918f079..fdf75892e 100644
--- a/tests/monster_test_generated.ts
+++ b/tests/monster_test_generated.ts
@@ -356,13 +356,7 @@ a():number {
  * @returns boolean
  */
 mutate_a(value:number):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 0);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeInt16(this.bb_pos + offset, value);
+  this.bb!.writeInt16(this.bb_pos + 0, value);
   return true;
 };
 
@@ -378,13 +372,7 @@ b():number {
  * @returns boolean
  */
 mutate_b(value:number):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 2);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeInt8(this.bb_pos + offset, value);
+  this.bb!.writeInt8(this.bb_pos + 2, value);
   return true;
 };
 
@@ -604,13 +592,7 @@ x():number {
  * @returns boolean
  */
 mutate_x(value:number):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 0);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeFloat32(this.bb_pos + offset, value);
+  this.bb!.writeFloat32(this.bb_pos + 0, value);
   return true;
 };
 
@@ -626,13 +608,7 @@ y():number {
  * @returns boolean
  */
 mutate_y(value:number):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 4);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeFloat32(this.bb_pos + offset, value);
+  this.bb!.writeFloat32(this.bb_pos + 4, value);
   return true;
 };
 
@@ -648,13 +624,7 @@ z():number {
  * @returns boolean
  */
 mutate_z(value:number):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 8);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeFloat32(this.bb_pos + offset, value);
+  this.bb!.writeFloat32(this.bb_pos + 8, value);
   return true;
 };
 
@@ -670,13 +640,7 @@ test1():number {
  * @returns boolean
  */
 mutate_test1(value:number):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 16);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeFloat64(this.bb_pos + offset, value);
+  this.bb!.writeFloat64(this.bb_pos + 16, value);
   return true;
 };
 
@@ -692,13 +656,7 @@ test2():MyGame.Example.Color {
  * @returns boolean
  */
 mutate_test2(value:MyGame.Example.Color):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 24);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeUint8(this.bb_pos + offset, value);
+  this.bb!.writeUint8(this.bb_pos + 24, value);
   return true;
 };
 
@@ -833,13 +791,7 @@ id():number {
  * @returns boolean
  */
 mutate_id(value:number):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 0);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeUint32(this.bb_pos + offset, value);
+  this.bb!.writeUint32(this.bb_pos + 0, value);
   return true;
 };
 
@@ -855,13 +807,7 @@ distance():number {
  * @returns boolean
  */
 mutate_distance(value:number):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 4);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeUint32(this.bb_pos + offset, value);
+  this.bb!.writeUint32(this.bb_pos + 4, value);
   return true;
 };
 
diff --git a/tests/namespace_test/namespace_test1_generated.js b/tests/namespace_test/namespace_test1_generated.js
index 256dce7df..2886cccbf 100644
--- a/tests/namespace_test/namespace_test1_generated.js
+++ b/tests/namespace_test/namespace_test1_generated.js
@@ -171,13 +171,7 @@ NamespaceA.NamespaceB.StructInNestedNS.prototype.a = function() {
  * @returns {boolean}
  */
 NamespaceA.NamespaceB.StructInNestedNS.prototype.mutate_a = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 0);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeInt32(this.bb_pos + offset, value);
+  this.bb.writeInt32(this.bb_pos + 0, value);
   return true;
 };
 
@@ -193,13 +187,7 @@ NamespaceA.NamespaceB.StructInNestedNS.prototype.b = function() {
  * @returns {boolean}
  */
 NamespaceA.NamespaceB.StructInNestedNS.prototype.mutate_b = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 4);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeInt32(this.bb_pos + offset, value);
+  this.bb.writeInt32(this.bb_pos + 4, value);
   return true;
 };
 
diff --git a/tests/namespace_test/namespace_test1_generated.ts b/tests/namespace_test/namespace_test1_generated.ts
index eb59054d0..fde55fbbc 100644
--- a/tests/namespace_test/namespace_test1_generated.ts
+++ b/tests/namespace_test/namespace_test1_generated.ts
@@ -170,13 +170,7 @@ a():number {
  * @returns boolean
  */
 mutate_a(value:number):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 0);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeInt32(this.bb_pos + offset, value);
+  this.bb!.writeInt32(this.bb_pos + 0, value);
   return true;
 };
 
@@ -192,13 +186,7 @@ b():number {
  * @returns boolean
  */
 mutate_b(value:number):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 4);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeInt32(this.bb_pos + offset, value);
+  this.bb!.writeInt32(this.bb_pos + 4, value);
   return true;
 };
 
diff --git a/tests/union_vector/union_vector_generated.js b/tests/union_vector/union_vector_generated.js
index 2507c31f2..8b8c765a0 100644
--- a/tests/union_vector/union_vector_generated.js
+++ b/tests/union_vector/union_vector_generated.js
@@ -167,13 +167,7 @@ Rapunzel.prototype.hairLength = function() {
  * @returns {boolean}
  */
 Rapunzel.prototype.mutate_hair_length = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 0);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeInt32(this.bb_pos + offset, value);
+  this.bb.writeInt32(this.bb_pos + 0, value);
   return true;
 };
 
@@ -226,13 +220,7 @@ BookReader.prototype.booksRead = function() {
  * @returns {boolean}
  */
 BookReader.prototype.mutate_books_read = function(value) {
-  var offset = this.bb.__offset(this.bb_pos, 0);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb.writeInt32(this.bb_pos + offset, value);
+  this.bb.writeInt32(this.bb_pos + 0, value);
   return true;
 };
 
diff --git a/tests/union_vector/union_vector_generated.ts b/tests/union_vector/union_vector_generated.ts
index d8f9f4f37..402f04fc5 100644
--- a/tests/union_vector/union_vector_generated.ts
+++ b/tests/union_vector/union_vector_generated.ts
@@ -202,13 +202,7 @@ hairLength():number {
  * @returns boolean
  */
 mutate_hair_length(value:number):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 0);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeInt32(this.bb_pos + offset, value);
+  this.bb!.writeInt32(this.bb_pos + 0, value);
   return true;
 };
 
@@ -290,13 +284,7 @@ booksRead():number {
  * @returns boolean
  */
 mutate_books_read(value:number):boolean {
-  var offset = this.bb!.__offset(this.bb_pos, 0);
-
-  if (offset === 0) {
-    return false;
-  }
-
-  this.bb!.writeInt32(this.bb_pos + offset, value);
+  this.bb!.writeInt32(this.bb_pos + 0, value);
   return true;
 };