diff --git a/examples/flow/output/test/test_grpc_js.js b/examples/flow/output/test/test_grpc_js.js
index deec380..27088ef 100644
--- a/examples/flow/output/test/test_grpc_js.js
+++ b/examples/flow/output/test/test_grpc_js.js
@@ -6,51 +6,63 @@ import test_pb from './test_pb'
 
 
 export type TestEnum = {|
-    ELEMENT_A: 0;
-    ELEMENT_B: 1;
+    ELEMENT_A?: 0;
+    ELEMENT_B?: 1;
 |};
 
 
 export type TestMessage$TestNestedEnum = {|
-    ELEMENT_C: 0;
-    ELEMENT_D: 1;
+    ELEMENT_C?: 0;
+    ELEMENT_D?: 1;
 |};
 
 
 export type TestMessage$TestNestedMessage = {
-    getS: () => string;
-    setS: (s: string) => void;
-    getT: () => number;
-    setT: (t: number) => void;
+    getS?: () => string;
+    setS?: (s: string) => void;
+    getT?: () => number;
+    setT?: (t: number) => void;
 };
 
 export type TestMessage = {
-    getA: () => string;
-    setA: (a: string) => void;
-    getB: () => number;
-    setB: (b: number) => void;
-    getC: () => number;
-    setC: (c: number) => void;
-    getD: () => number;
-    setD: (d: number) => void;
-    getE: () => number;
-    setE: (e: number) => void;
-    getN: () => Array<string>;
-    setN: (n: Array<string>) => void;
-    getO: () => Array<number>;
-    setO: (o: Array<number>) => void;
-    getP: () => Array<number>;
-    setP: (p: Array<number>) => void;
-    getQ: () => Array<number>;
-    setQ: (q: Array<number>) => void;
-    getR: () => Array<number>;
-    setR: (r: Array<number>) => void;
-    getU: () => TestEnum;
-    setU: (u: TestEnum) => void;
-    getV: () => TestMessage$TestNestedEnum;
-    setV: (v: TestMessage$TestNestedEnum) => void;
-    getW: () => Array<TestMessage$TestNestedMessage>;
-    setW: (w: Array<TestMessage$TestNestedMessage>) => void;
+    getA?: () => string;
+    setA?: (a: string) => void;
+    getB?: () => number;
+    setB?: (b: number) => void;
+    getC?: () => number;
+    setC?: (c: number) => void;
+    getD?: () => number;
+    setD?: (d: number) => void;
+    getE?: () => number;
+    setE?: (e: number) => void;
+    getNList?: () => Array<string>;
+    setNList?: (n: Array<string>) => void;
+    addN?: (n: string) => void;
+    clearNList?: () => void;
+    getOList?: () => Array<number>;
+    setOList?: (o: Array<number>) => void;
+    addO?: (o: number) => void;
+    clearOList?: () => void;
+    getPList?: () => Array<number>;
+    setPList?: (p: Array<number>) => void;
+    addP?: (p: number) => void;
+    clearPList?: () => void;
+    getQList?: () => Array<number>;
+    setQList?: (q: Array<number>) => void;
+    addQ?: (q: number) => void;
+    clearQList?: () => void;
+    getRList?: () => Array<number>;
+    setRList?: (r: Array<number>) => void;
+    addR?: (r: number) => void;
+    clearRList?: () => void;
+    getU?: () => TestEnum;
+    setU?: (u: TestEnum) => void;
+    getV?: () => TestMessage$TestNestedEnum;
+    setV?: (v: TestMessage$TestNestedEnum) => void;
+    getWList?: () => Array<TestMessage$TestNestedMessage>;
+    setWList?: (w: Array<TestMessage$TestNestedMessage>) => void;
+    addW?: (w: TestMessage$TestNestedMessage) => void;
+    clearWList?: () => void;
 };
 
 
@@ -58,8 +70,10 @@ export type TestMessage = {
 
 
 export type TestNoStreamRequest = {
-    getMessage: () => TestMessage;
-    setMessage: (message: TestMessage) => void;
+    getMessage?: () => TestMessage;
+    setMessage?: (message: TestMessage) => void;
+    clearMessage?: () => void;
+    hasMessage?: () => boolean;
 };
 
 
@@ -67,10 +81,12 @@ export type TestNoStreamRequest = {
 
 
 export type TestNoStreamReply = {
-    getMessage: () => TestMessage;
-    setMessage: (message: TestMessage) => void;
-    getErrMsg: () => string;
-    setErrMsg: (err_msg: string) => void;
+    getMessage?: () => TestMessage;
+    setMessage?: (message: TestMessage) => void;
+    clearMessage?: () => void;
+    hasMessage?: () => boolean;
+    getErrMsg?: () => string;
+    setErrMsg?: (err_msg: string) => void;
 };
 
 
@@ -78,8 +94,10 @@ export type TestNoStreamReply = {
 
 
 export type TestStreamRequestRequest = {
-    getMessage: () => TestMessage;
-    setMessage: (message: TestMessage) => void;
+    getMessage?: () => TestMessage;
+    setMessage?: (message: TestMessage) => void;
+    clearMessage?: () => void;
+    hasMessage?: () => boolean;
 };
 
 
@@ -87,10 +105,12 @@ export type TestStreamRequestRequest = {
 
 
 export type TestStreamRequestReply = {
-    getMessage: () => TestMessage;
-    setMessage: (message: TestMessage) => void;
-    getErrMsg: () => string;
-    setErrMsg: (err_msg: string) => void;
+    getMessage?: () => TestMessage;
+    setMessage?: (message: TestMessage) => void;
+    clearMessage?: () => void;
+    hasMessage?: () => boolean;
+    getErrMsg?: () => string;
+    setErrMsg?: (err_msg: string) => void;
 };
 
 
@@ -98,8 +118,10 @@ export type TestStreamRequestReply = {
 
 
 export type TestStreamReplyRequest = {
-    getMessage: () => TestMessage;
-    setMessage: (message: TestMessage) => void;
+    getMessage?: () => TestMessage;
+    setMessage?: (message: TestMessage) => void;
+    clearMessage?: () => void;
+    hasMessage?: () => boolean;
 };
 
 
@@ -107,10 +129,12 @@ export type TestStreamReplyRequest = {
 
 
 export type TestStreamReplyReply = {
-    getMessage: () => TestMessage;
-    setMessage: (message: TestMessage) => void;
-    getErrMsg: () => string;
-    setErrMsg: (err_msg: string) => void;
+    getMessage?: () => TestMessage;
+    setMessage?: (message: TestMessage) => void;
+    clearMessage?: () => void;
+    hasMessage?: () => boolean;
+    getErrMsg?: () => string;
+    setErrMsg?: (err_msg: string) => void;
 };
 
 
@@ -118,8 +142,10 @@ export type TestStreamReplyReply = {
 
 
 export type TestStreamBothRequest = {
-    getMessage: () => TestMessage;
-    setMessage: (message: TestMessage) => void;
+    getMessage?: () => TestMessage;
+    setMessage?: (message: TestMessage) => void;
+    clearMessage?: () => void;
+    hasMessage?: () => boolean;
 };
 
 
@@ -127,10 +153,12 @@ export type TestStreamBothRequest = {
 
 
 export type TestStreamBothReply = {
-    getMessage: () => TestMessage;
-    setMessage: (message: TestMessage) => void;
-    getErrMsg: () => string;
-    setErrMsg: (err_msg: string) => void;
+    getMessage?: () => TestMessage;
+    setMessage?: (message: TestMessage) => void;
+    clearMessage?: () => void;
+    hasMessage?: () => boolean;
+    getErrMsg?: () => string;
+    setErrMsg?: (err_msg: string) => void;
 };
 
 const serializeToBase64 = (byteArray: Uint8Array): string => base64.fromByteArray(byteArray)
diff --git a/examples/flow/templates/{{.File.Package}}/{{.File.Package}}_grpc_js.js.tmpl b/examples/flow/templates/{{.File.Package}}/{{.File.Package}}_grpc_js.js.tmpl
index 4b7eae7..e4cc024 100644
--- a/examples/flow/templates/{{.File.Package}}/{{.File.Package}}_grpc_js.js.tmpl
+++ b/examples/flow/templates/{{.File.Package}}/{{.File.Package}}_grpc_js.js.tmpl
@@ -10,10 +10,27 @@ import {{$Package}}_pb from './{{$Package}}_pb'
 import {{. | replace "/" "_" | trimSuffix ".proto" }}_pb from '../{{. | trimSuffix ".proto" }}_pb'
 {{- end}}
 
+{{- define "fieldMethods"}}
+  {{- if isFieldRepeated .}}
+    get{{.Name | camelCase}}List?: () => {{. | jsType}};
+    set{{.Name | camelCase}}List?: ({{.Name}}: {{. | jsType}}) => void;
+    add{{.Name | camelCase}}?: ({{.Name}}: {{. | jsType | trimPrefix "Array<" | trimSuffix ">"}}) => void;
+    clear{{.Name | camelCase}}List?: () => void;
+  {{- else}}
+    get{{.Name | camelCase}}?: () => {{. | jsType}};
+    set{{.Name | camelCase}}?: ({{.Name}}: {{. | jsType}}) => void;
+
+    {{- if isFieldMessage .}}
+    clear{{.Name | camelCase}}?: () => void;
+    has{{.Name | camelCase}}?: () => boolean;
+    {{- end}}
+  {{- end}}
+{{- end}}
+
 {{range .File.EnumType}}
 export type {{.Name}} = {|
   {{- range .Value}}
-    {{.Name}}: {{.Number}};
+    {{.Name}}?: {{.Number}};
   {{- end}}
 |};
 {{- end}}
@@ -24,7 +41,7 @@ export type {{.Name}} = {|
 {{range .EnumType}}
 export type {{$MessageType}}${{.Name}} = {|
   {{- range .Value}}
-    {{.Name}}: {{.Number}};
+    {{.Name}}?: {{.Number}};
   {{- end}}
 |};
 {{- end}}
@@ -32,16 +49,14 @@ export type {{$MessageType}}${{.Name}} = {|
 {{range .NestedType}}
 export type {{$MessageType}}${{.Name}} = {
   {{- range .Field}}
-    {{.Name | getter}}: () => {{. | jsType}};
-    {{.Name | setter}}: ({{.Name}}: {{. | jsType}}) => void;
+    {{- template "fieldMethods" .}}
   {{- end}}
 };
 {{- end}}
 
 export type {{.Name}} = {
   {{- range .Field}}
-    {{.Name | getter}}: () => {{. | jsType}};
-    {{.Name | setter}}: ({{.Name}}: {{. | jsType}}) => void;
+    {{- template "fieldMethods" .}}
   {{- end}}
 };
 
diff --git a/helpers.go b/helpers.go
index d4648bf..6aaccf5 100644
--- a/helpers.go
+++ b/helpers.go
@@ -50,17 +50,16 @@ var ProtoHelpersFuncMap = template.FuncMap{
 
 		return strings.ToUpper(s[:1])
 	},
+	"lowerCamelCase": func(s string) string {
+		if len(s) > 1 {
+			s = xstrings.ToCamelCase(s)
+		}
 
+		return strings.ToLower(s[:1]) + s[1:]
+	},
 	"kebabCase": func(s string) string {
 		return strings.Replace(xstrings.ToSnakeCase(s), "_", "-", -1)
 	},
-	"getter": func(s string) string {
-		return toLowerCamelCase("get_" + s)
-	},
-	"setter": func(s string) string {
-		return toLowerCamelCase("set_" + s)
-	},
-	"lowerCamelCase":  toLowerCamelCase,
 	"snakeCase":       xstrings.ToSnakeCase,
 	"getMessageType":  getMessageType,
 	"isFieldMessage":  isFieldMessage,
@@ -78,14 +77,6 @@ func init() {
 	}
 }
 
-func toLowerCamelCase(s string) string {
-	if len(s) > 1 {
-		s = xstrings.ToCamelCase(s)
-	}
-
-	return strings.ToLower(s[:1]) + s[1:]
-}
-
 func getMessageType(f *descriptor.FileDescriptorProto, name string) *descriptor.DescriptorProto {
 	// name is in the form .packageName.MessageTypeName.InnerMessageTypeName...
 	// e.g. .article.ProductTag