Skip to content

docs: add structured clone and transferable API reference #3101

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
bartlomieju wants to merge 1 commit into
base: main
Choose a base branch
from
Open

docs: add structured clone and transferable API reference #3101

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
48 changes: 48 additions & 0 deletions api/web/index.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,54 @@ Deno supports a comprehensive set of web standard APIs:
- **[Timers](/api/web/~/setTimeout)** - setTimeout, setInterval, and
setImmediate

### Structured Clone & Transferable Objects

Deno supports [`structuredClone()`](/api/web/~/structuredClone) and
[`postMessage()`](/api/web/~/Worker) for cloning and transferring objects across
contexts (e.g. between the main thread and Web Workers).

#### Serializable types

These types can be cloned with `structuredClone()` and sent via `postMessage()`:

| Type | Notes |
| --- | --- |
| Primitives | `string`, `number`, `boolean`, `null`, `undefined`, `bigint` |
| `Array`, `Object`, `Map`, `Set` | Including nested structures and circular references |
| `Date`, `RegExp` | |
| `ArrayBuffer`, `TypedArray`, `DataView` | Copied by default, or transferred (see below) |
| `Error` types | `Error`, `EvalError`, `RangeError`, `ReferenceError`, `SyntaxError`, `TypeError`, `URIError` |
| [`Blob`](/api/web/~/Blob) | |
| [`File`](/api/web/~/File) | |
| [`DOMException`](/api/web/~/DOMException) | |
| [`CryptoKey`](/api/web/~/CryptoKey) | |

#### Transferable types

These types can be _transferred_ (not copied) via the `transfer` option in
`structuredClone()` or the `transfer` list in `postMessage()`. After transfer,
the original object becomes unusable:

| Type | Notes |
| --- | --- |
| [`ArrayBuffer`](/api/web/~/ArrayBuffer) | Moves the backing memory to the receiver |
| [`MessagePort`](/api/web/~/MessagePort) | Transfers the port to another context |
| [`ReadableStream`](/api/web/~/ReadableStream) | Transfers the stream to another context |
| [`WritableStream`](/api/web/~/WritableStream) | Transfers the stream to another context |
| [`TransformStream`](/api/web/~/TransformStream) | Transfers the stream to another context |

```ts
// Clone a Blob
const blob = new Blob(["hello"], { type: "text/plain" });
const cloned = structuredClone(blob);
console.log(await cloned.text()); // "hello"

// Transfer an ArrayBuffer to a worker
const buffer = new ArrayBuffer(1024);
worker.postMessage(buffer, [buffer]);
// buffer.byteLength is now 0 (transferred)
```

## Key Benefits

- **Standards Compliance**: APIs follow WHATWG and W3C specifications
Expand Down
48 changes: 48 additions & 0 deletions runtime/reference/web_platform_apis.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -489,6 +489,54 @@ const worker = new Worker(import.meta.resolve("./worker.js"), {
});
```

## Structured Clone & Transferable Objects

Deno supports [`structuredClone()`](/api/web/~/structuredClone) and
[`postMessage()`](/api/web/~/Worker) for cloning and transferring objects across
contexts (e.g. between the main thread and Web Workers).

### Serializable types

These types can be cloned with `structuredClone()` and sent via `postMessage()`:

| Type | Notes |
| --- | --- |
| Primitives | `string`, `number`, `boolean`, `null`, `undefined`, `bigint` |
| `Array`, `Object`, `Map`, `Set` | Including nested structures and circular references |
| `Date`, `RegExp` | |
| `ArrayBuffer`, `TypedArray`, `DataView` | Copied by default, or transferred (see below) |
| `Error` types | `Error`, `EvalError`, `RangeError`, `ReferenceError`, `SyntaxError`, `TypeError`, `URIError` |
| [`Blob`](/api/web/~/Blob) | |
| [`File`](/api/web/~/File) | |
| [`DOMException`](/api/web/~/DOMException) | |
| [`CryptoKey`](/api/web/~/CryptoKey) | |

### Transferable types

These types can be _transferred_ (not copied) via the `transfer` option in
`structuredClone()` or the `transfer` list in `postMessage()`. After transfer,
the original object becomes unusable:

| Type | Notes |
| --- | --- |
| [`ArrayBuffer`](/api/web/~/ArrayBuffer) | Moves the backing memory to the receiver |
| [`MessagePort`](/api/web/~/MessagePort) | Transfers the port to another context |
| [`ReadableStream`](/api/web/~/ReadableStream) | Transfers the stream to another context |
| [`WritableStream`](/api/web/~/WritableStream) | Transfers the stream to another context |
| [`TransformStream`](/api/web/~/TransformStream) | Transfers the stream to another context |

```ts
// Clone a Blob
const blob = new Blob(["hello"], { type: "text/plain" });
const cloned = structuredClone(blob);
console.log(await cloned.text()); // "hello"

// Transfer an ArrayBuffer to a worker
const buffer = new ArrayBuffer(1024);
worker.postMessage(buffer, [buffer]);
// buffer.byteLength is now 0 (transferred)
```

## Deviations of other APIs from spec

### Cache API
Expand Down
Loading