An Introduction to Deno for Node.js Developers

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Deno and Node.js have a lot in common. They are both non-browser JavaScript runtimes built on the V8 engine. Deno and Node.js are also different in a lot of ways: TypeScript, CommonJS, package management, permission systems, tooling, native addons, browser compatibility. This talk will compare and contrast the two runtimes, focusing on what experienced Node.js developers need to know in order to succeed with Deno.

This talk has been presented at JSNation 2022, check out the latest edition of this JavaScript Conference.

FAQ

Both Deno and Node.js are JavaScript runtimes built on Google's V8 JavaScript engine, used for building server-side applications. Both environments support TypeScript and are used for similar types of projects.

Deno is designed to be secure by default. It operates in a sandbox environment where no file, network, or environment access is allowed without explicit permission. Deno requires specific flags to grant script access to different system resources, enhancing security and preventing unauthorized actions.

In Deno, modules are imported directly from URLs and are cached locally. There is no central package.json file; instead, each module can be versioned independently by specifying version numbers in the import URL. Deno also supports the use of a 'deno.json' configuration file for more complex dependency management.

Yes, Deno has first-class support for TypeScript. The runtime includes a built-in TypeScript compiler, and there is no need for additional tooling or configuration to use TypeScript with Deno.

Deno Deploy is a globally distributed JavaScript VM that allows you to run JavaScript programs at the edge. It is designed for cloud deployment, supporting 32 edge locations with plans for expansion. Deno Deploy is currently in public beta and can deploy code globally in under 10 seconds.

Deno does not have a traditional package manager like NPM. Instead, it imports modules directly via URLs and caches them locally. Deno can also bundle all dependencies locally using the 'deno vendor' command for production environments. For third-party modules, Deno uses its own hosting service at deno.land/x.

Yes, Deno has a compatibility mode for running Node.js code. By using the '--compat' flag and potentially the '--unstable' flag, developers can utilize Node.js features like 'require' in Deno.

Deno is a JavaScript runtime built on the V8 engine, similar to Node.js, but it incorporates several key differences. It is written in Rust, offers built-in utilities like a linter and formatter, and is designed to be secure by default with a comprehensive permission system. Unlike Node.js, Deno does not use NPM or 'node_modules' but uses imports from URLs.

Colin Ihrig
Colin Ihrig
22 min
20 Jun, 2022

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Video Summary and Transcription
This Talk provides an introduction to Deno for Node.js developers, highlighting the differences in architecture and dependencies between the two runtimes. It discusses the Deno CLI and integrated toolchain, the Deno standard library and dependency management, as well as the Deno runtime and its core features. The Talk also covers Deno's permission system, its focus on web platform compatibility, and its support for TypeScript. Overall, it provides a comprehensive overview of Deno and its advantages over Node.js.

1. Introduction to Deno for Node.js Developers

Short description:

I'm going to be talking about getting started with deno if you are a node.js developer. I've been using node for about 10 years and just recently started working at deno. Node.js has been around significantly longer since around 2009, and then deno came out around 10 years after that. The interesting thing about node.js is that it predates a lot of what we consider to be modern JavaScript. Dno has taken a different approach, where it's much more batteries included. It has an integrated tool chain and a number of other things. Node.js has a huge ecosystem with a lot of legacy code. Having a huge ecosystem is nice, but having to support so much legacy code can actually slow down a lot of progress and actually kind of hinder Node's ability to have standards compliance.

Hi, everybody. Thanks for coming to my talk. I'm going to be talking about getting started with deno if you are a node.js developer. So a little bit of personal background on myself. I've been using node for about 10 years and just recently started working at deno. So it's been, you know, a learning experience trying to switch between these two environments. So I was hoping that this talk could help somebody else who was in my shoes with moving over to deno.

A little bit of background on both run times. They're both JavaScript run times. They're both built on the V8 engine. Node.js has been around significantly longer since around 2009, and then deno came out around 10 years after that. The interesting thing about node.js is that it predates a lot of what we consider to be modern JavaScript. So for example, it still supports CommonJS, even though it has ES modules. It still has its legacy callback APIs, even though it now has support for a lot of promise-based APIs. Node has also historically, although it has changed a lot in recent years, taken a kind of defer everything to user land approach. So the idea was that core would be very minimal, and that user land would implement NPM modules for a lot of other functionality. I would say that Dno has taken a different approach, where it's much more batteries included. It has an integrated tool chain and a number of other things, which I'll talk about later in these slides. Another thing is that Node.js has a huge ecosystem with a lot of legacy code. This can be good and bad, so having a huge ecosystem is nice. But having to support so much legacy code can actually slow down a lot of progress and actually kind of hinder Node's ability to have standards compliance, which is something else I'll get into later in the slides.

2. Deno Timeline, DenoDeploy, and Growth

Short description:

The timeline for Deno, the release of Deno 1.0.0, the announcement of the Deno company, and the introduction of DenoDeploy. DenoDeploy is a globally distributed JavaScript VM for cloud deployment. The growth of Deno in terms of GitHub stars compared to Node.js. Next, the core technologies under the two projects will be discussed.

So the timeline for Dno is roughly shown here. So in June of 2018, Dno was first introduced at JS Conf EU. Later that year in August, Dno 0.1.0 was released, and it was rewritten in Rust. So initially, the native parts of Dno were written in Golang. And they were kind of moved over to Rust because there was kind of concern about having multiple with garbage collectors running in the same process.

So then in May of 2020, Dno 1.0.0 was was finally released. So then in March of 2021, the Dno company was announced. So this is nice, because having a company backing a project can can really help because you can lay out a roadmap. You can allocate workers to work on specific things, and just generally have better control of how the project is going to be developed. On the other hand, Node.js is run by almost all volunteers. So you know, we can't really, on the Node side, control who's going to work on what. We can't tell volunteers to spend their time on certain features. And we've even had initiatives like Node's Benchmarking Working Group, which is doing a lot of useful work, have to be wound down because there just was nobody that was working on them at the time. So having a company backing the project is huge, in my opinion.

So then in June of 2021, DenoDeploy was announced. So DenoDeploy is a very similar runtime to the open source Deno project, except it's meant to be deployed in the cloud. It's more or less a globally distributed JavaScript VM that lets you run JavaScript programs at the edge all over the world. So there's currently 32 different edge locations that are supported and we're constantly adding more. It's nice because you can write your code and have it deployed in less than 10 seconds globally. And then in Q3 of this year, we are aiming to get DenoDeploy to general availability. And right now it's still in a public beta.

So I wanted to talk quickly about the growth here. So this graph shows GitHub stars for the Deno CLI as well as Node.js. The graph would only generate back to around 2015, even though Node actually goes back to 2009. So that arrow shown there should actually be wider. GitHub stars are kind of a proxy metric for adoption. Anyone can star a GitHub repository without actually using the project. But we do have some internal metrics that indicate that this growth is real and not just fluff on GitHub. So I think based on the 10-year age difference in the two projects, the difference in stars is really something that is worth kind of noting. Next, I want to talk about the core technologies that are under the two projects.

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