WebTransportSendStream: getWriter() method

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Note: This feature is available in Web Workers.

The getWriter() method of the WebTransportSendStream interface returns a new WebTransportWriter object and locks the stream to that instance. While the stream is locked, no other writer can be acquired until this one is released.

WebTransportWriter is a subclass of WritableStreamDefaultWriter that additionally provides the atomicWrite() and commit() methods.

Syntax

js
getWriter()

Parameters

None.

Return value

A WebTransportWriter object instance.

Exceptions

TypeError

The stream is already locked to another writer.

Examples

The following example shows how to open a unidirectional stream over a WebTransport connection and use getWriter() to write chunks of data to it.

js
const transport = new WebTransport("https://example.com/webtransport");
await transport.ready;

const stream = await transport.createUnidirectionalStream();
const writer = stream.getWriter();

const encoder = new TextEncoder();
await writer.write(encoder.encode("Hello"));
await writer.write(encoder.encode(", world!"));
await writer.close();

Specifications

Specification
WebTransport
# dom-webtransportsendstream-getwriter

Browser compatibility

desktop mobile server
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
getWriter
Chrome – No support
Chrome
footnote No support
Edge – No support
Edge
footnote No support
Firefox – Full support
Firefox 114 (Release date: 2023-06-06)
footnote Full support
Opera – No support
Opera
footnote No support
Safari – Full support
Safari 26.4 (Release date: 2026-03-24)
footnote Full support
Chrome Android – No support
Chrome Android
footnote No support
Firefox for Android – Full support
Firefox for Android 114 (Release date: 2023-06-06)
footnote Full support
Opera Android – No support
Opera Android
footnote No support
Safari on iOS – Full support
Safari on iOS 26.4 (Release date: 2026-03-24)
footnote Full support
Samsung Internet – No support
Samsung Internet
footnote No support
WebView Android – No support
WebView Android
footnote No support
WebView on iOS – Full support
WebView on iOS 26.4 (Release date: 2026-03-24)
footnote Full support
Deno – No support
Deno 2.2 (Release date: 2025-02-19)
disabled
disabled From version 2.2 users must explicitly set the --unstable-net runtime flag.

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
No support
No support
User must explicitly enable this feature.

See also