Add allowResizable to (Shared)ArrayBuffer conversions

Implements the [AllowResizable] attribute introduced in whatwg/webidl#982.

Author: MattiasBuelens

README.md

@@ -56,11 +56,11 @@ Conversions for all of the basic types from the Web IDL specification are implem
 - [`DOMString`](https://heycam.github.io/webidl/#es-DOMString), which can additionally be provided the boolean option `{ treatNullAsEmptyString }` as a second parameter
 - [`ByteString`](https://heycam.github.io/webidl/#es-ByteString), [`USVString`](https://heycam.github.io/webidl/#es-USVString)
 - [`object`](https://heycam.github.io/webidl/#es-object)
-- [Buffer source types](https://heycam.github.io/webidl/#es-buffer-source-types), which can additionally be provided with the boolean option `{ allowShared }` as a second parameter
+- [Buffer source types](https://heycam.github.io/webidl/#es-buffer-source-types), which can additionally be provided with the boolean option bag `{ allowShared, allowResizable }` as a second parameter
 
 Additionally, for convenience, the following derived type definitions are implemented:
 
-- [`ArrayBufferView`](https://heycam.github.io/webidl/#ArrayBufferView), which can additionally be provided with the boolean option `{ allowShared }` as a second parameter
+- [`ArrayBufferView`](https://heycam.github.io/webidl/#ArrayBufferView), which can additionally be provided with the boolean option bag `{ allowShared, allowResizable }` as a second parameter
 - [`BufferSource`](https://heycam.github.io/webidl/#BufferSource)
 - [`DOMTimeStamp`](https://heycam.github.io/webidl/#DOMTimeStamp)
 

lib/index.js

@@ -322,6 +322,25 @@ function isSharedArrayBuffer(value) {
   }
 }
 
+const abResizableGetter = Object.getOwnPropertyDescriptor(ArrayBuffer.prototype, "resizable").get;
+const sabGrowableGetter = Object.getOwnPropertyDescriptor(SharedArrayBuffer.prototype, "growable").get;
+
+function isNonSharedArrayBufferResizable(value) {
+  try {
+    return abResizableGetter.call(value);
+  } catch {
+    return false;
+  }
+}
+
+function isSharedArrayBufferGrowable(value) {
+  try {
+    return sabGrowableGetter.call(value);
+  } catch {
+    return false;
+  }
+}
+
 function isArrayBufferDetached(value) {
   try {
     // eslint-disable-next-line no-new
@@ -336,6 +355,9 @@ exports.ArrayBuffer = (value, options = {}) => {
   if (!isNonSharedArrayBuffer(value)) {
     throw makeException(TypeError, "is not an ArrayBuffer", options);
   }
+  if (!options.allowResizable && isNonSharedArrayBufferResizable(value)) {
+    throw makeException(TypeError, "is a resizable ArrayBuffer", options);
+  }
   if (isArrayBufferDetached(value)) {
     throw makeException(TypeError, "is a detached ArrayBuffer", options);
   }
@@ -347,8 +369,8 @@ exports.SharedArrayBuffer = (value, options = {}) => {
   if (!isSharedArrayBuffer(value)) {
     throw makeException(TypeError, "is not a SharedArrayBuffer", options);
   }
-  if (isArrayBufferDetached(value)) {
-    throw makeException(TypeError, "is a detached SharedArrayBuffer", options);
+  if (!options.allowResizable && isSharedArrayBufferGrowable(value)) {
+    throw makeException(TypeError, "is a growable SharedArrayBuffer", options);
   }
 
   return value;
@@ -405,6 +427,14 @@ exports.ArrayBufferView = (value, options = {}) => {
     throw makeException(TypeError, "is a view on a SharedArrayBuffer, which is not allowed", options);
   }
 
+  if (!options.allowResizable) {
+    if (isNonSharedArrayBufferResizable(value.buffer)) {
+      throw makeException(TypeError, "is a view on a resizable ArrayBuffer, which is not allowed", options);
+    } else if (isSharedArrayBufferGrowable(value.buffer)) {
+      throw makeException(TypeError, "is a view on a growable SharedArrayBuffer, which is not allowed", options);
+    }
+  }
+
   if (isArrayBufferDetached(value.buffer)) {
     throw makeException(TypeError, "is a view on a detached ArrayBuffer", options);
   }