CompressionStream: writable property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨May 2023⁩.

Note: This feature is available in Web Workers.

The writable read-only property of the CompressionStream interface returns a WritableStream that accepts uncompressed data to be compressed, in the form of ArrayBuffer, TypedArray, or DataView chunks.

Value

A WritableStream.

Examples

This example creates a CompressionStream that performs gzip compression. It writes some binary data to the writable stream, then reads the compressed data from the readable stream.

const stream = new CompressionStream("gzip");

// Write data to be compressed
const data = new TextEncoder().encode("Hello, world!");
const writer = stream.writable.getWriter();
writer.write(data);
writer.close();

// Read compressed data
const reader = stream.readable.getReader();
let done = false;
let output = [];
while (!done) {
  const result = await reader.read();
  if (result.value) {
    output.push(...result.value);
  }
  done = result.done;
}
console.log(new Uint8Array(output).toBase64()); // H4sIAAAAAAAAE/NIzcnJ11Eozy/KSVEEAObG5usNAAAA