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Deno 1.11 Release Notes

June 8th, 2021
Luca Casonato, Bartek Iwańczuk, Ryan Dahl, Kitson Kelly

Deno 1.11 has been tagged and released with the follow features:

If you already have Deno installed you can upgrade to 1.11 by running

deno upgrade

If you are installing Deno for the first time, you can use one of the methods listed below:

# Using Shell (macOS and Linux):
curl -fsSL | sh

# Using PowerShell (Windows):
iwr -useb | iex

# Using Homebrew (macOS):
brew install deno

# Using Scoop (Windows):
scoop install deno

# Using Chocolatey (Windows):
choco install deno

Official Docker images

There are now official Docker images for Deno available on Dockerhub.

To start the deno repl:

$ docker run -it --init denoland/deno:1.11.0 repl

To shell into the docker runtime:

$ docker run -it --init --entrypoint sh denoland/deno:1.11.0

To run main.ts from your working directory:

$ docker run -it --init -p 1993:1993 -v $PWD:/app denoland/deno:1.11.0 run --allow-net /app/main.ts

Here, -p 1993:1993 maps port 1993 on the container to 1993 on the host, -v $PWD:/app mounts the host working directory to /app on the container, and --allow-net /app/main.ts is passed to deno on the container.

Thank you to Andy Hayden who maintained the Deno Docker images over the past two years.

More Web Crypto APIs supported

This release marks the start of our efforts to add the Web Crypto API to Deno. It exposes cryptographic primitives to your application, that can be used to easily build secure systems using cryptography. We have supported crypto.getRandomValues() since Deno 1.0, but we have now added support for hashing and UUID generation.

You can now securely hash data using the sha-256, sha-384, sha-512, or sha-1 algorithms using the SubtleCrypto.digest API, also available in browsers and Node.js. Here is an example:

import { encodeToString } from "[email protected]/encoding/hex.ts";
const data = new TextEncoder().encode("Deno 1.11 has been released!");
const digest = await crypto.subtle.digest("sha-256", data.buffer);
console.log("Digest:", encodeToString(new Uint8Array(digest)));

Additionally we have added support for the recently standardized crypto.randomUUID function. It allows you to generate UUID v4 as per RFC 4122. This feature is already in Node.js and will ship in Chrome/Edge 92 by the end of next month.

console.log("Random UUID:", crypto.randomUUID());

We aim to expand the Web Crypto APIs in the next release, Deno 1.12, scheduled for July 13th.

Abortable fetch

Sometimes it is desirable to abort an ongoing fetch, for example if you want to time out a request if it has not responded after a few seconds. This release adds support for aborting fetch using an AbortSignal, the web standard API for aborting fetches. Here is an example of how this works:

// To get an `AbortSignal`, you must create an `AbortController`. This is used to
// tell the `AbortSignal` when it is time to abort.
const controller = new AbortController();
// Register a timeout to abort the fetch after 5 seconds.
// In a real application you would want to cancel this timeout after the request is done.
setTimeout(() => controller.abort(), 5000);

// Fetch a URL, passing the `signal` property from the created `AbortController`.
// If the abort signal triggers while the request is being sent, or response headers
// are being received, this will reject.
const response = await fetch("", {
  signal: controller.signal,
// Parse the response. Note, that this must also complete before the abort signal
// triggers, otherwise receiving the response will be terminated and `response.json`
// will reject.
const users = await response.json();

A request can be aborted in all parts of its lifecycle, so during sending headers to the server, sending a body to the server, receiving back headers, or receiving back the response body.

deno lint is now stable

Deno ships with a built-in linter available as deno lint sub-command.

It was first introduced in v1.1.0 back in June 2020, but as a precaution it required --unstable flag when using deno lint to signal that the linter is still early in development and might have bugs.

Over the following months deno_lint went through a few rounds of refactors to improve its stability as well as adding more rules to match recommended set from ESLint.

We were still receiving feedback that some users don't want to use deno lint yet, because it's unstable. In v1.10.0 we removed requirement for --unstable flag, and today we're happy to announce that deno lint is considered stable. However, we still reserve the right to change set of recommended rules.

Thank you to Yusuke Tanaka who contributed countless PRs over the months and implemented a lot of rules.

Updates to deno compile

Producing self contained binaries has been the most requested feature in Deno's issue tracker and first landed in v1.6.

The functionality provided was limited in scope and one of missing features that was highly requested was using dynamic imports inside produced binaries. This release adds support for dynamic imports using data URIs which allows to read a source file from disk or remote location and execute it. Please keep in mind that importing directly from file system or remote location is still not supported.


// some_source_code.js
console.log("Hello Deno!");
const sourceCode = await Deno.readTextFile("./some_source_code.js");
const dataUrl = "data:text/javascript;base64," + btoa(sourceCode);
const c = await import(dataUrl);
console.log(c.default); // Output: "Hello Deno!"

Another highly requested feature for self contained binaries was access to the runtime compiler API (Deno.emit()). We're happy to announce that this API is now be available in all produced binaries.

TextEncoderStream and TextDecoderStream

This release adds support for two modern web APIs: TextEncoderStream and TextDecoderStream. These stream combinators can be used with ReadableStream to easily decode a stream from bytes to string or from string to bytes.

Here is an example where we pipe a fetch response body stream through a TextDecoderStream. This converts the stream of raw bytes into a string of string segments. This example will print each segment to the console on a new line.

const response = await fetch("");
const body = response.body.pipeThrough(new TextDecoderStream());
for await (const chunk of body) {
  console.log("!!chunk start!!", chunk, "!!chunk end!!");

In addition we also now support the stream option on standard TextDecoder.


In this release we are prototyping support for BroadcastChannel under --unstable. BroadcastChannel can be used to broadcast messages consisting of complex JavaScript objects between workers. Currently this is restricted to workers in the same process, but in the future we want to allow BroadcastChannel to communicate between multiple processes sharing an origin (an origin is the protocol, hostname, and port of the URL you can pass to --location).

Here is an example of broadcasting a message to three workers:

const c = new BroadcastChannel("foo");
const url = new URL("./worker.js", import.meta.url).href;

for (let i = 0; i < 3; i++) {
  const w = new Worker(url, { type: "module" });
  await new Promise((resolve) => w.onmessage = resolve); // Wait for ready.

c.postMessage({ hello: [1, 2, 3] });

And the worker.js module:

const c = new BroadcastChannel("foo");
c.onmessage = (e) => {
  console.log("got message",;

More details about broadcast channels can be found on MDN.

Updates to deno lsp

This release brings a number of features to the language server:

Test code lens

LSP now provides code lenses for tests, which allow clients to launch the Deno CLI executing specific tests identified in the IDE.

test code lens

For Visual Studio Code, you need version 3.6.0 or later of the vscode_deno extension to take advantage of this feature.

Support for per resource configuration

The LSP now supports per resource configuration as part of the LSP protocol. In Visual Studio Code, this manifests itself as multi-root workspaces which allow you to have specific configurations for different folders. Also checkout out the workspace folders documentation in the vscode_deno extension for more information.

Registry auto discovery

In Deno 1.10 we added support for import completions for remote registries. Previously you had to manually register remote registries you want to get completions for in your LSP settings. With this release the Deno extension will prompt you if it discovers that an registry you are importing supports registry import completions. You can opt out of auto discovery by setting the deno.suggest.imports.autoDiscover extension option to false.

registry auto discover

Support formatting JSON(C) and Markdown files

In addition to formatting JavaScript, JSX, TypeScript and TSX file, LSP can now format JSON, JSONC and Markdown files as well.

LSP formatter

Show X-Deno-Warning header as a diagnostic

When serving source code CDNs can provide X-Deno-Warning header that will be displayed when first downloading the source code. Now LSP can show those warnings inline. For example: when using warnings are shown if URL has no version included.

X-Deno-Warning header

Show hints in the linter diagnostics

Deno LSP provides diagnostics from the built-in linter and with this release it will display hints alongside the diagnostics.

Previously (1.10):

linter hint before

Now (1.11):

linter hint after

Show diagnostics for @deno-types and triple-slash refs

LSP can now understand // @deno-types and /// <reference /> comments and will provide diagnostics for those comments.

Updates to stable APIs

Following Deno APIs added support for using argument of type URL instead of string for arguments that represent filepath (URL with scheme other than file:// will not work).

This change is backwards compatible.

TypeScript 4.3

Deno 1.11 ships with the latest stable version of TypeScript. For more information on new features in TypeScript see Announcing TypeScript 4.3

Web compatibility and ecosystem updates

With every release we are continuing our work on improving the compatibility between APIs in Deno and APIs in web browsers.

One way we are doing this is by sharing a test suite with browsers like Chrome, Firefox, Safari, and Servo. This shared web platform test suite checks that all browsers adhere to the same web platform specifications, so your code can be portable across engines.

You can now view our progress towards web compatibility on our new web platform test dashboard at It displays the status of all the WPTs we execute in our continuous integration flow. We are also working with Philip Jägenstedt from the Chromium ecosystem infrastructure team to get Deno compatibility data on This will allow for comparisons between different versions of Deno, or between Deno and other browser engines.

We are also working on getting Deno compatibility data displayed on MDN so you can figure out what APIs Deno supports, right on the canonical source of documentation for Web APIs.