What is Node.js?
Node's approach to scaling with callback functions requires less memory to handle more connections than most competitive architectures that scale with threads, including Apache HTTP Server, the various Java application servers, IIS and ASP.NET, and Ruby on Rails.
Much of Node's utility comes from its large package library, which is accessible from the
npm command. NPM, the Node Package Manager, is part of the standard Node.js installation, although it has its own website.
What is Deno?
Node's module system problem was solved by an update in mid-2022.
CommonJS and ECMAScript modules
npm originally supported. Since then, the ECMAScript committee officially blessed ECMAScript modules, also known as ES modules, which is supported by the
jspm package manager. Deno also supports ES modules.
Experimental support for ES modules was added in Node.js 12.12 and is stable from Node.js 16 forward. TypeScript 4.7 also supports ES modules for Node.js 16.
require statement. The way to load an ECMAScript module is to use an
import statement along with a matching
The latest Node.js has loaders for both CommonJS and ES modules. How are they different? The CommonJS loader is fully synchronous; is responsible for handling
require() calls; supports folders as modules; and tries adding extensions (.js, .json, or .node) if one was omitted from the
require() call. The CommonJS loader cannot be used to load ECMAScript modules. The ES modules loader is asynchronous; is responsible for handling both import statements and
import() expressions; does not support folders as modules (directory indexes such as
Why Deno is better for security
It is well known that Deno improves security over Node. Mainly, this is because Deno, by default, does not let a program access disk, network, subprocesses, or environmental variables. When you need to allow any of these, you can opt-in with a command-line flag, which can be as granular as you like; for example,
--allow-net=google.com. Another security improvement in Deno is that it always dies on uncaught errors. Node, by contrast, will allow execution to proceed after an uncaught error, with unpredictable results.
Can you use Node.js and Deno together?
First off, many times, using Node packages from Deno just works. Even better, there are workarounds for many of the common stumbling blocks. These include using the
std/node modules of the Deno standard library to "polyfill" the built-in modules of Node; using CDNs to access the vast majority of
npm packages in ways that work under Deno; and using import maps. Moreover, Deno has a Node compatibility mode starting with Deno 1.15.
On the downside, Node’s plugin system is incompatible with Deno; Deno’s Node compatibility mode doesn’t support TypeScript; and a few built-in Node modules (such as vm) are incompatible with Deno.
If you’re a Node user thinking of switching to Deno, here’s a cheat sheet to help you.
Using TypeScript with Deno
swc. When the code has been type-checked (if checking is enabled) and transformed, it is stored in a cache. In other words, unlike Node.js or a browser, you don’t need to manually transpile your TypeScript for Deno with the
As of Deno 1.23, there is no TypeScript type-checking in Deno by default. Since most developers interact with the type-checker through their editor, type-checking again when Deno starts up doesn’t make a lot of sense. That said, you can enable type-checking with the
--check flag to Deno.
NodeJS or Deno?
As you might expect, the answer of which technology is better for your use case depends on many factors. My bottom line: If you have an existing Node.js deployment that isn’t broken, then don’t fix it. If you have a new project that you intend to write in TypeScript, then I'd strongly consider Deno. However, if your TypeScript project needs to use multiple Node.js packages that do not have Deno equivalents, you will need to weigh the Deno project's feasibility. Starting with a proof-of-concept is pretty much mandatory: It’s hard to predict whether you can make a given Node.js package work in Deno without trying it.