update readme

README.md

@@ -10,34 +10,90 @@ Stage: 1
 
 ## Presentations
 
-- [For stage 1 on 82th tc39 meeting (Apr 2021)](https://docs.google.com/presentation/d/1TGLvflOG63C5iHush597ffKTenoYowc3MivQEhAM20w/edit?usp=sharing)
-- [TC39 meeting notes on 82th tc39 meeting](https://github.com/tc39/notes/blob/master/meetings/2021-04/apr-21.md#read-only-arraybuffer-and-fixed-view-of-arraybuffer-for-stage-1)
+- [TC39 meeting notes on 82th tc39 meeting](https://github.com/tc39/notes/blob/main/meetings/2021-04/apr-21.md#read-only-arraybuffer-and-fixed-view-of-arraybuffer-for-stage-1) ([slides](https://docs.google.com/presentation/d/1TGLvflOG63C5iHush597ffKTenoYowc3MivQEhAM20w/edit?usp=sharing))
+- [TC39 meeting notes on 106 tc39 meeting](https://github.com/tc39/notes/blob/main/meetings/2025-02/) ([slides](https://docs.google.com/presentation/d/1u6JsSeInvm6F4OrmCSLubtDvFVdjw1ESeE5-c_YflHE/))
 
 ## Problem to be resolved
 
 All of the following are helpful to archive the minimal permission/information principle.
 
-1. Cannot make an `ArrayBuffer` read-only.
-2. Cannot give others a read-only view to the `ArrayBuffer` and keep the read-write permission internally.
-3. Cannot give others a view that range limited (only a small area of the whole buffer is visible).
+1. Cannot give others a read-only view to the `ArrayBuffer` and keep the read-write view internally.
+2. Cannot give others a view that range is limited.
+
+```js
+function createView() {
+    const buffer = new ArrayBuffer(128)
+    const offset = 4
+    const length = 16
+    const view = new Uint8Array(buffer, offset, length)
+    view[0] = 0x12
+    return view
+}
+
+const view = createView()
+// oops!
+const wholeBufferView = new Uint8Array(view.buffer)
+```
 
 ## Design goal
 
-1. Freeze the `ArrayBuffer`.
-    1. Like `Object.freeze`, there is no way back once frozen.
-    2. Any `TypedArray`/`DataView` to the freezed `ArrayBuffer` is read-only too.
-    3. [Optional] Keep frozen when sent across Realm (HTML intergration).
-2. Read-only `TypedArray`/`DataView` to a read-write `ArrayBuffer`.
+1. Read-only `TypedArray`/`DataView` to a read-write `ArrayBuffer`.
     1. Must not be able to construct a read-write view from a read-only view.
-3. [Optional] Range-limited `TypedArray`/`DataView` to a read-write `ArrayBuffer` ([CrimsonCodes0](https://github.com/CrimsonCodes0)'s [use case on WebAssembly](https://github.com/tc39/proposal-limited-arraybuffer/issues/11)).
+1. Range-limited `TypedArray`/`DataView` to a read-write `ArrayBuffer`.
     1. Must not be able to construct a bigger view range from a smaller view range.
-4. Not adding too much complexity to the implementor.
+1. Not adding too much complexity to the implementor.
+
+## Proposed changes
+
+1. New API on the `TypedArray`/`DataView` constructor.
+
+```ts
+interface TypedArrayConstructor {
+    new (buffer: ArrayBuffer, options?: TypedArrayConstructorOptionsBag): Uint8Array<ArrayBuffer>;
+}
+interface DataViewConstructor {
+    new (buffer: ArrayBuffer, options?: ViewConstructorOptionsBag): DataView<ArrayBuffer>;
+}
+interface ViewConstructorOptionsBag {
+    byteOffset?: number;
+    length?: number;
+    readonly?: boolean;
+    limited?: boolean;
+}
+```
+
+1. If `readonly` or `limited` is set, the view returned does not have a `.buffer` property on it.
+
+```ts
+const buffer = new ArrayBuffer(1024);
+const view = new Uint8Array(buffer, { limited: true, byteOffset: 12 });
+view.buffer; // undefined
+```
+
+1. If `readonly` is set, the `TypedArray` returned is an exotic object (behaves like a [`ModuleNamespaceExoticObject`](https://tc39.es/ecma262/multipage/ordinary-and-exotic-objects-behaviours.html#module-namespace-exotic-object)), the returned `DataView` throws for set functions.
+
+```ts
+const buffer = new ArrayBuffer(8);
+const view = new Uint8Array(buffer, { readonly: true });
+view.buffer; // undefined
+// view[0] = 1; // Error
+Object.getOwnPropertyDescriptor(view, 0);
+// { configurable: false, writable: true, enumerable: true, value: 0 }
+
+const view2 = new DataView(buffer, { readonly: true });
+view2.buffer; // undefined
+// view2.setUint8(0, 0); // Error
+```
 
-## Pros
+1. Change the constructor of `TypedArray` and `DataView`, to accept `TypedArray` and `DataView` as source.
 
-1. Minimal permission/information principle works on `ArrayBuffer`.
-2. Embedded JS engines can represent ROMs as read-only `ArrayBuffer`.
+```ts
+const buffer = new ArrayBuffer(128)
+const view = new Uint8Array(buffer, { offset: 16, length: 32, readonly: true })
 
-## API design
+const dataView = new DataView(view)
+dataView.setUint32(0, 1) // throws, inherits readonly, offset and length of `view`
 
-See [design.md](./design.md)
+const dataView2 = new DataView(view, 16, 16)
+// inherits readonly, offset += 16 (32 in total), length = 16
+```