WebTransport: datagrams property

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 insecure contexts (HTTPS), in some or allsupporting browsers.

Note: This feature is available inWeb Workers.

Thedatagrams read-only property of theWebTransport interface returns aWebTransportDatagramDuplexStream instance that can be used to send and receive datagrams — unreliable data transmission.

"Unreliable" means that transmission of data is not guaranteed, nor is arrival in a specific order. This is fine in some situations and provides very fast delivery. For example, you might want to transmit regular game state updates where each message supersedes the last one that arrives, and order is not important.

Value

AWebTransportDatagramDuplexStream object.

Examples

Writing an outgoing datagram

TheWebTransportDatagramDuplexStream.writable property returns aWritableStream object that you can write data to using a writer, for transmission to the server:

const writer = transport.datagrams.writable.getWriter();const data1 = new Uint8Array([65, 66, 67]);const data2 = new Uint8Array([68, 69, 70]);writer.write(data1);writer.write(data2);

Reading an incoming datagram

TheWebTransportDatagramDuplexStream.readable property returns aReadableStream object that you can use to receive data from the server:

async function readData() {  const reader = transport.datagrams.readable.getReader();  while (true) {    const { value, done } = await reader.read();    if (done) {      break;    }    // value is a Uint8Array.    console.log(value);  }}