feat(streams): to ArrayBuffer/Blob/Json/Text

streams/mod.ts

@@ -23,6 +23,10 @@ export * from "./reader_from_iterable.ts";
 export * from "./reader_from_stream_reader.ts";
 export * from "./text_delimiter_stream.ts";
 export * from "./text_line_stream.ts";
+export * from "./to_array_buffer.ts";
+export * from "./to_blob.ts";
+export * from "./to_json.ts";
+export * from "./to_text.ts";
 export * from "./to_transform_stream.ts";
 export * from "./writable_stream_from_writer.ts";
 export * from "./write_all.ts";

streams/to_array_buffer.ts

@@ -0,0 +1,23 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+// This module is browser compatible.
+
+import { concat } from "../bytes/concat.ts";
+
+export async function toArrayBuffer(
+  readableStream: ReadableStream<Uint8Array>,
+): Promise<ArrayBuffer> {
+  const reader = readableStream.getReader();
+  const chunks: Uint8Array[] = [];
+
+  while (true) {
+    const { done, value } = await reader.read();
+
+    if (done) {
+      break;
+    }
+
+    chunks.push(value);
+  }
+
+  return concat(...chunks).buffer;
+}

streams/to_array_buffer_test.ts

@@ -0,0 +1,18 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+import { assertEquals } from "../assert/assert_equals.ts";
+import { toArrayBuffer } from "./to_array_buffer.ts";
+
+Deno.test("[streams] toArrayBuffer", async () => {
+  const stream = new ReadableStream<Uint8Array>({
+    start(controller) {
+      controller.enqueue(Uint8Array.of(1, 2, 3, 4, 5));
+      controller.enqueue(Uint8Array.of(6, 7));
+      controller.enqueue(Uint8Array.of(8, 9));
+      controller.close();
+    },
+  });
+
+  const buf = await toArrayBuffer(stream);
+  assertEquals(buf, Uint8Array.of(1, 2, 3, 4, 5, 6, 7, 8, 9).buffer);
+});

streams/to_blob.ts

@@ -0,0 +1,21 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+// This module is browser compatible.
+
+export async function toBlob(
+  readableStream: ReadableStream,
+): Promise<Blob> {
+  const reader = readableStream.getReader();
+  const chunks: Uint8Array[] = [];
+
+  while (true) {
+    const { done, value } = await reader.read();
+
+    if (done) {
+      break;
+    }
+
+    chunks.push(value);
+  }
+
+  return new Blob(chunks);
+}

streams/to_blob_test.ts

@@ -0,0 +1,23 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+import { assert } from "../assert/assert.ts";
+import { assertEquals } from "../assert/assert_equals.ts";
+import { toBlob } from "./to_blob.ts";
+
+Deno.test("[streams] toBlob", async () => {
+  const stream = new ReadableStream<Uint8Array>({
+    start(controller) {
+      controller.enqueue(Uint8Array.of(1, 2, 3, 4, 5));
+      controller.enqueue(Uint8Array.of(6, 7));
+      controller.enqueue(Uint8Array.of(8, 9));
+      controller.close();
+    },
+  });
+
+  const blob = await toBlob(stream);
+  assert(blob instanceof Blob);
+  assertEquals(
+    await blob.arrayBuffer(),
+    Uint8Array.of(1, 2, 3, 4, 5, 6, 7, 8, 9).buffer,
+  );
+});

streams/to_json.ts

@@ -0,0 +1,10 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+// This module is browser compatible.
+
+import { toText } from "./to_text.ts";
+
+export function toJson(
+  readableStream: ReadableStream,
+): Promise<unknown> {
+  return toText(readableStream).then(JSON.parse);
+}

streams/to_json_test.ts

@@ -0,0 +1,34 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+import { assertEquals } from "../assert/assert_equals.ts";
+import { toJson } from "./to_json.ts";
+
+const textEncoder = new TextEncoder();
+
+Deno.test("[streams] toJson", async () => {
+  const byteStream = new ReadableStream<Uint8Array>({
+    start(controller) {
+      controller.enqueue(textEncoder.encode("["));
+      controller.enqueue(textEncoder.encode("1, 2, 3, 4"));
+      controller.enqueue(textEncoder.encode("]"));
+      controller.close();
+    },
+  });
+
+  assertEquals(await toJson(byteStream), [1, 2, 3, 4]);
+
+  const stringStream = new ReadableStream<string>({
+    start(controller) {
+      controller.enqueue('{ "a": 2,');
+      controller.enqueue(' "b": 3,');
+      controller.enqueue(' "c": 4 }');
+      controller.close();
+    },
+  });
+
+  assertEquals(await toJson(stringStream), {
+    a: 2,
+    b: 3,
+    c: 4,
+  });
+});

streams/to_text.ts

@@ -0,0 +1,23 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+// This module is browser compatible.
+
+const textDecoder = new TextDecoder();
+
+export async function toText(
+  readableStream: ReadableStream,
+): Promise<string> {
+  const reader = readableStream.getReader();
+  let result = "";
+
+  while (true) {
+    const { done, value } = await reader.read();
+
+    if (done) {
+      break;
+    }
+
+    result += typeof value === "string" ? value : textDecoder.decode(value);
+  }
+
+  return result;
+}

streams/to_text_test.ts

@@ -0,0 +1,30 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+import { assertEquals } from "../assert/assert_equals.ts";
+import { toText } from "./to_text.ts";
+
+const textEncoder = new TextEncoder();
+
+Deno.test("[streams] toText", async () => {
+  const byteStream = new ReadableStream<Uint8Array>({
+    start(controller) {
+      controller.enqueue(textEncoder.encode("hello"));
+      controller.enqueue(textEncoder.encode(" js "));
+      controller.enqueue(textEncoder.encode("fans"));
+      controller.close();
+    },
+  });
+
+  assertEquals(await toText(byteStream), "hello js fans");
+
+  const stringStream = new ReadableStream<string>({
+    start(controller) {
+      controller.enqueue("hello");
+      controller.enqueue(" deno ");
+      controller.enqueue("world");
+      controller.close();
+    },
+  });
+
+  assertEquals(await toText(stringStream), "hello deno world");
+});