chore: add compression utilities for browser

packages/middleware-compression/src/compressStream.browser.ts

@@ -0,0 +1,2 @@
+export const compressStream = async (body: ReadableStream): Promise<ReadableStream> =>
+  body.pipeThrough(new CompressionStream("gzip"));

packages/middleware-compression/src/compressString.browser.ts

@@ -0,0 +1,38 @@
+import { toUint8Array } from "@smithy/util-utf8";
+
+import { compressStream } from "./compressStream.browser";
+import { CompressionAlgorithm } from "./constants";
+
+export const compressString = async (body: any, algorithm: CompressionAlgorithm): Promise<Uint8Array> => {
+  // Only gzip shall be supported initial release.
+  if (algorithm !== CompressionAlgorithm.GZIP) {
+    throw new Error(`Only '${CompressionAlgorithm.GZIP}' is supported for compression. Got '${algorithm}'.`);
+  }
+
+  const inputUint8Array = toUint8Array(body);
+  const inputStream = new ReadableStream({
+    start(controller) {
+      controller.enqueue(inputUint8Array);
+      controller.close();
+    },
+  });
+
+  const outputStream = await compressStream(inputStream);
+
+  const reader = outputStream.getReader();
+  const chunks: Uint8Array[] = [];
+  while (true) {
+    const { done, value } = await reader.read();
+    if (done) {
+      break;
+    }
+    chunks.push(...value);
+  }
+
+  return new Uint8Array(
+    chunks.reduce((acc, chunk) => {
+      acc.push(...chunk);
+      return acc;
+    }, [])
+  );
+};