It all started 2 years ago, Ryan Dahl, the creator of Node.js gave a talk at the JSConf 2018 "10 Things I Regret About Node.js"
It was actually 7 things 🙃he regrets about Node.js:
1. Not sticking with Promises: he added them in June 2009 but removed them in February 2010, with Promises in Node.js, It could have sped up the delivery of a standard on async/await
2. Security: Node process has wide access including system calls, network, disk I/O
3. The build system: You need GYP for compiling native C library and link it to Node.js modules, Chrome used to use GYB but now Node is the sole user
4. package.json: it includes unnecessary information such as LICENCES and repository - also it uses a centralized repository for modules
5. node_modules: maybe the worse for him, resolution is complex, folder size is frequently huge...
6. require without extension: the module load has to guess the extension and this is not how browser works
7. index.js: it complicates the module loading system
With all the things learned by building Node.js, Ryan came up with a new idea named [Deno](https://deno.land/):
A secure runtime for JavaScript and TypeScript.
Deno aims to provide a productive and secure scripting environment for the modern programmer.
It is built on top of V8, Rust, and TypeScript. Instead of using C++ as in Node.js, It's built on top of Rust and It uses Tokio under the hood.It brings many of the best open-source technologies together.
So after almost 2 years, the API has been officially frozen and the launch of the 1.0 is scheduled on May 13. It addresses the design flaws that Ryan talked about in his lecture.
To install Deno, here are the instructions:
Using Shell:
bashcurl -fsSL https://deno.land/x/install/install.sh | sh
Or using PowerShell:
iwr https://deno.land/x/install/install.ps1 -useb | iex
Using Homebrew (macOS or Linux):
brew install deno
Using Chocolatey (Windows):
choco install deno
See deno_install for more installation options.
Deno 1.0 comes fully loaded with many useful features for modern development. In the following section we are going to cover all the greatest features coming in the new release.
Well, everything is in the title. You can also bring your own
tsconfig.json
by using the following command: deno run -c tsconfig.json [program.ts]
Programs run with no permissions by default and if the code needs permissions will be alerted. You need to use command-line options to tell Deno what permissions the program needs.
By running
deno run -h
you will see the full list of permissions.Deno does not support
require(),
It uses ES Modules:import * as log from "https://deno.land/std/log/mod.ts";
The package management is super simple, just provide the URL of what you want to use. As the URL may change, for security purposes, by using a lock file (using the --lock command line flag) you can ensure you're running the code you expect to be.
Deno does not use npm. It uses modules referenced as URLs or file paths:
import { serve } from "https://deno.land/[email protected]/http/server.ts";
const s = serve({ port: 8000 });
for await (const req of s) {
req.respond({ body: "Hello World\n" });
}
You can specify version of the package in directly in the URL. For example
https://deno.land/[email protected]/http/server.ts
. Also, Deno offers a built-in dependency inspector (deno info
).The Deno convention for dependency management is using a unique file called
deps.ts
for storing all the dependency. For example, we can look at the deps.ts
of oak, the popular middleware framework for Deno's http server inspired by Koa:// Copyright 2018-2020 the oak authors. All rights reserved. MIT license.
// This file contains the external dependencies that oak depends upon
export {
HTTPOptions,
HTTPSOptions,
Response,
serve,
Server,
ServerRequest,
serveTLS,
} from "https://deno.land/[email protected]/http/server.ts";
export {
Status,
STATUS_TEXT,
} from "https://deno.land/[email protected]/http/http_status.ts";
export {
Cookies,
Cookie,
setCookie,
getCookies,
delCookie,
} from "https://deno.land/[email protected]/http/cookie.ts";
export {
basename,
extname,
join,
isAbsolute,
normalize,
parse,
resolve,
sep,
} from "https://deno.land/[email protected]/path/mod.ts";
export { HmacSha256 } from "https://deno.land/[email protected]/util/sha256.ts";
export { assert } from "https://deno.land/[email protected]/testing/asserts.ts";
export {
contentType,
lookup,
} from "https://deno.land/x/[email protected]/mod.ts";
(Source: https://github.com/oakserver/oak/blob/master/deps.ts)
deno doc
We strive for complete documentation. Deno has JSDoc built-in so you can use write JSDoc comments in files.
Deno.test()
std/testing/asserts.ts
module provides range of assertion helpers:equal()
assert()
assertEquals()
assertNotEquals()
assertStrictEq()
assertStrContains()
assertMatch()
assertArrayContains()
assertThrows()
assertThrowsAsync()
unimplemented()
unreachable()
import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
Deno.test({
name: "testing example",
fn(): void {
assertEquals("world", "world");
assertEquals({ hello: "world" }, { hello: "world" });
},
});
(Source: https://github.com/denoland/deno/tree/master/std/testing)
Run
deno test file.spec.ts
:Compile file.spec.ts
Download https://deno.land/std/testing/asserts.ts
Download https://deno.land/std/fmt/colors.ts
Download https://deno.land/std/testing/diff.ts
running 1 tests
test testing example ... ok (9ms)
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out (9ms)
deno fmt <files>
It is provided by dprint, an alternative to the famour Prettier.
deno bundle
It is currently marked as unstable. So use it at your own risk.
deno run -A --inspect-brk fileToDebug.ts
With this you can open the Chrome debugger (
chrome://inspect
) and start inspect the process!The standard library is garanteed to work with Deno, they do not have external dependencies and they are reviewed by the Deno core team. Modules are tagged in accordance with Deno releases, so version v0.4.0 of a standard library is garanteed to work with Deno v0.4.0.
List of modules:
import { Application } from "https://deno.land/x/oak/mod.ts";
const app = new Application();
// Logger
app.use(async (ctx, next) => {
await next();
const rt = ctx.response.headers.get("X-Response-Time");
console.log(`${ctx.request.method} ${ctx.request.url} - ${rt}`);
});
// Hello World!
app.use((ctx) => {
ctx.response.body = "Hello World!";
});
await app.listen({ port: 8000 });
Let's run it using
deno server.ts
: Compile file:///.../server.ts
Download https://deno.land/x/oak/mod.ts
Download https://deno.land/x/oak/application.ts
Download https://deno.land/x/oak/context.ts
Download https://deno.land/x/oak/cookies.ts
Download https://deno.land/x/oak/httpError.ts
Download https://deno.land/x/oak/middleware.ts
Download https://deno.land/x/oak/request.ts
Download https://deno.land/x/oak/response.ts
Download https://deno.land/x/oak/router.ts
Download https://deno.land/x/oak/send.ts
Download https://deno.land/x/oak/types.ts
Download https://deno.land/x/oak/deps.ts
Download https://deno.land/x/oak/keyStack.ts
Download https://deno.land/x/oak/tssCompare.ts
Download https://deno.land/[email protected]/http/server.ts
Download https://deno.land/[email protected]/http/http_status.ts
Download https://deno.land/[email protected]/http/cookie.ts
Download https://deno.land/[email protected]/path/mod.ts
Download https://deno.land/[email protected]/util/sha256.ts
Download https://deno.land/[email protected]/testing/asserts.ts
Download https://deno.land/x/[email protected]/mod.ts
Download https://deno.land/[email protected]/encoding/utf8.ts
Download https://deno.land/[email protected]/io/bufio.ts
Download https://deno.land/[email protected]/util/async.ts
Download https://deno.land/[email protected]/http/io.ts
Download https://deno.land/[email protected]/io/util.ts
Download https://deno.land/[email protected]/path/win32.ts
Download https://deno.land/[email protected]/path/posix.ts
Download https://deno.land/[email protected]/path/constants.ts
Download https://deno.land/[email protected]/path/common.ts
Download https://deno.land/[email protected]/path/constants.ts
Download https://deno.land/[email protected]/path/interface.ts
Download https://deno.land/[email protected]/path/glob.ts
Download https://deno.land/[email protected]/path/globrex.ts
Download https://deno.land/[email protected]/path/utils.ts
Download https://deno.land/[email protected]/fmt/colors.ts
Download https://deno.land/[email protected]/testing/diff.ts
Download https://deno.land/[email protected]/textproto/mod.ts
Download https://deno.land/[email protected]/bytes/mod.ts
Download https://deno.land/[email protected]/datetime/mod.ts
Download https://deno.land/x/[email protected]/db.ts
Download https://deno.land/x/[email protected]/deps.ts
Download https://deno.land/[email protected]/path/mod.ts
Download https://deno.land/[email protected]/path/win32.ts
Download https://deno.land/[email protected]/path/posix.ts
Download https://deno.land/[email protected]/path/constants.ts
Download https://deno.land/[email protected]/path/common.ts
Download https://deno.land/[email protected]/path/constants.ts
Download https://deno.land/[email protected]/path/interface.ts
Download https://deno.land/[email protected]/path/glob.ts
Download https://deno.land/[email protected]/path/globrex.ts
Download https://deno.land/[email protected]/path/utils.ts
Download https://deno.land/[email protected]/testing/asserts.ts
Download https://deno.land/[email protected]/fmt/colors.ts
Download https://deno.land/[email protected]/testing/diff.ts
Download https://deno.land/x/oak/encoding.ts
Download https://deno.land/x/oak/isMediaType.ts
Download https://deno.land/x/oak/mediaType.ts
Download https://deno.land/x/oak/mediaTyper.ts
Download https://deno.land/x/oak/util.ts
Download https://deno.land/x/oak/pathToRegExp.ts
error: Uncaught PermissionDenied: network access to "127.0.0.1:8000", run again with the --allow-net flag
at unwrapResponse ($deno$/ops/dispatch_json.ts:43:11)
at Object.sendSync ($deno$/ops/dispatch_json.ts:72:10)
at Object.listen ($deno$/ops/net.ts:51:10)
at listen ($deno$/net.ts:164:18)
at Application.serve (server.ts:261:20)
at Application.listen (application.ts:106:31)
at server.ts:18:11
Let's add the missing permission
deno --allow-net server.ts
:$ curl http://127.0.0.1:8000
Hello World!
You are now ready for the upcoming release of Deno 1.0 - Stay tuned 😍 Please leave me comment if you've liked this article! You can also follow me on Twitter @loverdeolivier 🙌
This article was originally posted on my blog olivier.codes