diff --git a/feature_tests/js/api/OptionEnum.d.ts b/feature_tests/js/api/OptionEnum.d.ts
new file mode 100644
index 000000000..9c653bb63
--- /dev/null
+++ b/feature_tests/js/api/OptionEnum.d.ts
@@ -0,0 +1,14 @@
+// generated by diplomat-tool
+import type { pointer, codepoint } from "./diplomat-runtime.d.ts";
+
+// Base enumerator definition
+export class OptionEnum {
+    constructor(value : OptionEnum | string);
+
+    get value() : string;
+
+    get ffiValue() : number;
+
+    static Foo : OptionEnum;
+    static Bar : OptionEnum;
+}
\ No newline at end of file
diff --git a/feature_tests/js/api/OptionEnum.mjs b/feature_tests/js/api/OptionEnum.mjs
new file mode 100644
index 000000000..a0e362534
--- /dev/null
+++ b/feature_tests/js/api/OptionEnum.mjs
@@ -0,0 +1,53 @@
+// generated by diplomat-tool
+import wasm from "./diplomat-wasm.mjs";
+import * as diplomatRuntime from "./diplomat-runtime.mjs";
+
+// Base enumerator definition
+export class OptionEnum {
+    #value = undefined;
+
+    static #values = new Map([
+        ["Foo", 0],
+        ["Bar", 1]
+    ]);
+
+    constructor(value) {
+        if (arguments.length > 1 && arguments[0] === diplomatRuntime.internalConstructor) {
+            // We pass in two internalConstructor arguments to create *new*
+            // instances of this type, otherwise the enums are treated as singletons.
+            if (arguments[1] === diplomatRuntime.internalConstructor ) {
+                this.#value = arguments[2];
+                return;
+            }
+            return OptionEnum.#objectValues[arguments[1]];
+        }
+
+        if (value instanceof OptionEnum) {
+            return value;
+        }
+
+        let intVal = OptionEnum.#values.get(value);
+
+        // Nullish check, checks for null or undefined
+        if (intVal == null) {
+            return OptionEnum.#objectValues[intVal];
+        }
+
+        throw TypeError(value + " is not a OptionEnum and does not correspond to any of its enumerator values.");
+    }
+
+    get value() {
+        return [...OptionEnum.#values.keys()][this.#value];
+    }
+
+    get ffiValue() {
+        return this.#value;
+    }
+    static #objectValues = [
+        new OptionEnum(diplomatRuntime.internalConstructor, diplomatRuntime.internalConstructor, 0),
+        new OptionEnum(diplomatRuntime.internalConstructor, diplomatRuntime.internalConstructor, 1),
+    ];
+
+    static Foo = OptionEnum.#objectValues[0];
+    static Bar = OptionEnum.#objectValues[1];
+}
\ No newline at end of file
diff --git a/feature_tests/js/api/OptionInputStruct.d.ts b/feature_tests/js/api/OptionInputStruct.d.ts
new file mode 100644
index 000000000..9c14c45dd
--- /dev/null
+++ b/feature_tests/js/api/OptionInputStruct.d.ts
@@ -0,0 +1,16 @@
+// generated by diplomat-tool
+import type { OptionEnum } from "./OptionEnum"
+import type { pointer, codepoint } from "./diplomat-runtime.d.ts";
+
+export class OptionInputStruct {
+
+    get a() : number | null;
+    set a(value: number | null); 
+
+    get b() : codepoint | null;
+    set b(value: codepoint | null); 
+
+    get c() : OptionEnum | null;
+    set c(value: OptionEnum | null); 
+    constructor(a: number | null, b: codepoint | null, c: OptionEnum | null);
+}
\ No newline at end of file
diff --git a/feature_tests/js/api/OptionInputStruct.mjs b/feature_tests/js/api/OptionInputStruct.mjs
new file mode 100644
index 000000000..ba72bccf4
--- /dev/null
+++ b/feature_tests/js/api/OptionInputStruct.mjs
@@ -0,0 +1,76 @@
+// generated by diplomat-tool
+import { OptionEnum } from "./OptionEnum.mjs"
+import wasm from "./diplomat-wasm.mjs";
+import * as diplomatRuntime from "./diplomat-runtime.mjs";
+
+export class OptionInputStruct {
+
+    #a;
+    get a()  {
+        return this.#a;
+    }
+    set a(value) {
+        this.#a = value;
+    }
+
+    #b;
+    get b()  {
+        return this.#b;
+    }
+    set b(value) {
+        this.#b = value;
+    }
+
+    #c;
+    get c()  {
+        return this.#c;
+    }
+    set c(value) {
+        this.#c = value;
+    }
+    constructor() {
+        if (arguments.length > 0 && arguments[0] === diplomatRuntime.internalConstructor) {
+            this.#fromFFI(...Array.prototype.slice.call(arguments, 1));
+        } else {
+            
+            this.#a = arguments[0];
+            this.#b = arguments[1];
+            this.#c = arguments[2];
+        }
+    }
+
+    // Return this struct in FFI function friendly format.
+    // Returns an array that can be expanded with spread syntax (...)
+    
+    _intoFFI(
+        functionCleanupArena,
+        appendArrayMap
+    ) {
+        return [...diplomatRuntime.optionToArgsForCalling(this.#a, 1, 1, false, (arrayBuffer, offset, jsValue) => [diplomatRuntime.writeToArrayBuffer(arrayBuffer, offset + 0, jsValue, Uint8Array)]), /* [2 x i8] padding */ 0, 0 /* end padding */, ...diplomatRuntime.optionToArgsForCalling(this.#b, 4, 4, false, (arrayBuffer, offset, jsValue) => [diplomatRuntime.writeToArrayBuffer(arrayBuffer, offset + 0, jsValue, Uint32Array)]), ...diplomatRuntime.optionToArgsForCalling(this.#c, 4, 4, false, (arrayBuffer, offset, jsValue) => [diplomatRuntime.writeToArrayBuffer(arrayBuffer, offset + 0, jsValue.ffiValue, Int32Array)])]
+    }
+
+    _writeToArrayBuffer(
+        arrayBuffer,
+        offset,
+        functionCleanupArena,
+        appendArrayMap
+    ) {
+        diplomatRuntime.writeOptionToArrayBuffer(arrayBuffer, offset + 0, this.#a, 1, 1, (arrayBuffer, offset, jsValue) => diplomatRuntime.writeToArrayBuffer(arrayBuffer, offset + 0, jsValue, Uint8Array));
+        diplomatRuntime.writeOptionToArrayBuffer(arrayBuffer, offset + 4, this.#b, 4, 4, (arrayBuffer, offset, jsValue) => diplomatRuntime.writeToArrayBuffer(arrayBuffer, offset + 0, jsValue, Uint32Array));
+        diplomatRuntime.writeOptionToArrayBuffer(arrayBuffer, offset + 12, this.#c, 4, 4, (arrayBuffer, offset, jsValue) => diplomatRuntime.writeToArrayBuffer(arrayBuffer, offset + 0, jsValue.ffiValue, Int32Array));
+    }
+
+    // This struct contains borrowed fields, so this takes in a list of
+    // "edges" corresponding to where each lifetime's data may have been borrowed from
+    // and passes it down to individual fields containing the borrow.
+    // This method does not attempt to handle any dependencies between lifetimes, the caller
+    // should handle this when constructing edge arrays.
+    #fromFFI(ptr) {
+        const aDeref = ptr;
+        this.#a = diplomatRuntime.readOption(wasm, aDeref, 1, (wasm, offset) => { const deref = (new Uint8Array(wasm.memory.buffer, offset, 1))[0]; return deref });
+        const bDeref = ptr + 4;
+        this.#b = diplomatRuntime.readOption(wasm, bDeref, 4, (wasm, offset) => { const deref = (new Uint32Array(wasm.memory.buffer, offset, 1))[0]; return deref });
+        const cDeref = ptr + 12;
+        this.#c = diplomatRuntime.readOption(wasm, cDeref, 4, (wasm, offset) => { const deref = diplomatRuntime.enumDiscriminant(wasm, offset); return new OptionEnum(diplomatRuntime.internalConstructor, deref) });
+    }
+}
\ No newline at end of file
diff --git a/feature_tests/js/api/OptionOpaque.d.ts b/feature_tests/js/api/OptionOpaque.d.ts
index d1fa3016b..587d09ae1 100644
--- a/feature_tests/js/api/OptionOpaque.d.ts
+++ b/feature_tests/js/api/OptionOpaque.d.ts
@@ -1,4 +1,6 @@
 // generated by diplomat-tool
+import type { OptionEnum } from "./OptionEnum"
+import type { OptionInputStruct } from "./OptionInputStruct"
 import type { OptionStruct } from "./OptionStruct"
 import type { pointer, codepoint } from "./diplomat-runtime.d.ts";
 
@@ -28,4 +30,12 @@ export class OptionOpaque {
     assertInteger(i: number): void;
 
     static optionOpaqueArgument(arg: OptionOpaque | null): boolean;
+
+    static acceptsOptionU8(arg: number | null): number | null;
+
+    static acceptsOptionEnum(arg: OptionEnum | null): OptionEnum | null;
+
+    static acceptsOptionInputStruct(arg: OptionInputStruct | null): OptionInputStruct | null;
+
+    static returnsOptionInputStruct(): OptionInputStruct;
 }
\ No newline at end of file
diff --git a/feature_tests/js/api/OptionOpaque.mjs b/feature_tests/js/api/OptionOpaque.mjs
index cbaea364a..d099db5c4 100644
--- a/feature_tests/js/api/OptionOpaque.mjs
+++ b/feature_tests/js/api/OptionOpaque.mjs
@@ -1,4 +1,6 @@
 // generated by diplomat-tool
+import { OptionEnum } from "./OptionEnum.mjs"
+import { OptionInputStruct } from "./OptionInputStruct.mjs"
 import { OptionStruct } from "./OptionStruct.mjs"
 import wasm from "./diplomat-wasm.mjs";
 import * as diplomatRuntime from "./diplomat-runtime.mjs";
@@ -183,4 +185,73 @@ export class OptionOpaque {
         
         finally {}
     }
+
+    static acceptsOptionU8(arg) {
+        const diplomatReceive = new diplomatRuntime.DiplomatReceiveBuf(wasm, 2, 1, true);
+        
+        const result = wasm.OptionOpaque_accepts_option_u8(diplomatReceive.buffer, ...diplomatRuntime.optionToArgsForCalling(arg, 1, 1, false, (arrayBuffer, offset, jsValue) => [diplomatRuntime.writeToArrayBuffer(arrayBuffer, offset + 0, jsValue, Uint8Array)]));
+    
+        try {
+            if (!diplomatReceive.resultFlag) {
+                return null;
+            }
+            return (new Uint8Array(wasm.memory.buffer, diplomatReceive.buffer, 1))[0];
+        }
+        
+        finally {
+            diplomatReceive.free();
+        }
+    }
+
+    static acceptsOptionEnum(arg) {
+        const diplomatReceive = new diplomatRuntime.DiplomatReceiveBuf(wasm, 5, 4, true);
+        
+        const result = wasm.OptionOpaque_accepts_option_enum(diplomatReceive.buffer, ...diplomatRuntime.optionToArgsForCalling(arg, 4, 4, false, (arrayBuffer, offset, jsValue) => [diplomatRuntime.writeToArrayBuffer(arrayBuffer, offset + 0, jsValue.ffiValue, Int32Array)]));
+    
+        try {
+            if (!diplomatReceive.resultFlag) {
+                return null;
+            }
+            return new OptionEnum(diplomatRuntime.internalConstructor, diplomatRuntime.enumDiscriminant(wasm, diplomatReceive.buffer));
+        }
+        
+        finally {
+            diplomatReceive.free();
+        }
+    }
+
+    static acceptsOptionInputStruct(arg) {
+        let functionCleanupArena = new diplomatRuntime.CleanupArena();
+        
+        const diplomatReceive = new diplomatRuntime.DiplomatReceiveBuf(wasm, 21, 4, true);
+        
+        const result = wasm.OptionOpaque_accepts_option_input_struct(diplomatReceive.buffer, ...diplomatRuntime.optionToArgsForCalling(arg, 20, 4, false, (arrayBuffer, offset, jsValue) => [jsValue._writeToArrayBuffer(arrayBuffer, offset + 0, functionCleanupArena, {})]));
+    
+        try {
+            if (!diplomatReceive.resultFlag) {
+                return null;
+            }
+            return new OptionInputStruct(diplomatRuntime.internalConstructor, diplomatReceive.buffer);
+        }
+        
+        finally {
+            functionCleanupArena.free();
+        
+            diplomatReceive.free();
+        }
+    }
+
+    static returnsOptionInputStruct() {
+        const diplomatReceive = new diplomatRuntime.DiplomatReceiveBuf(wasm, 20, 4, false);
+        
+        const result = wasm.OptionOpaque_returns_option_input_struct(diplomatReceive.buffer);
+    
+        try {
+            return new OptionInputStruct(diplomatRuntime.internalConstructor, diplomatReceive.buffer);
+        }
+        
+        finally {
+            diplomatReceive.free();
+        }
+    }
 }
\ No newline at end of file
diff --git a/feature_tests/js/api/index.d.ts b/feature_tests/js/api/index.d.ts
index 6105033d2..6c5559c2d 100644
--- a/feature_tests/js/api/index.d.ts
+++ b/feature_tests/js/api/index.d.ts
@@ -12,6 +12,8 @@ export { BorrowedFieldsWithBounds } from "./BorrowedFieldsWithBounds"
 
 export { NestedBorrowedFields } from "./NestedBorrowedFields"
 
+export { OptionInputStruct } from "./OptionInputStruct"
+
 export { ErrorStruct } from "./ErrorStruct"
 
 export { BigStructWithStuff } from "./BigStructWithStuff"
@@ -76,6 +78,8 @@ export { RenamedAttrEnum } from "./RenamedAttrEnum"
 
 export { UnimportedEnum } from "./UnimportedEnum"
 
+export { OptionEnum } from "./OptionEnum"
+
 export { ErrorEnum } from "./ErrorEnum"
 
 export { ContiguousEnum } from "./ContiguousEnum"
diff --git a/feature_tests/js/api/index.mjs b/feature_tests/js/api/index.mjs
index c0b968bde..bf4c410dd 100644
--- a/feature_tests/js/api/index.mjs
+++ b/feature_tests/js/api/index.mjs
@@ -10,6 +10,8 @@ export { BorrowedFieldsWithBounds } from "./BorrowedFieldsWithBounds.mjs"
 
 export { NestedBorrowedFields } from "./NestedBorrowedFields.mjs"
 
+export { OptionInputStruct } from "./OptionInputStruct.mjs"
+
 export { ErrorStruct } from "./ErrorStruct.mjs"
 
 export { BigStructWithStuff } from "./BigStructWithStuff.mjs"
@@ -74,6 +76,8 @@ export { RenamedAttrEnum } from "./RenamedAttrEnum.mjs"
 
 export { UnimportedEnum } from "./UnimportedEnum.mjs"
 
+export { OptionEnum } from "./OptionEnum.mjs"
+
 export { ErrorEnum } from "./ErrorEnum.mjs"
 
 export { ContiguousEnum } from "./ContiguousEnum.mjs"
diff --git a/tool/src/js/mod.rs b/tool/src/js/mod.rs
index 13cfc1fa4..d7b36da7f 100644
--- a/tool/src/js/mod.rs
+++ b/tool/src/js/mod.rs
@@ -54,6 +54,7 @@ pub(crate) fn attr_support() -> BackendAttrSupport {
     a.iterables = true;
     a.indexing = false;
     a.callbacks = false;
+    a.option = true;
     a.traits = false;
 
     a