OK, so what is Deno? How is it different from Node? Why did you make Deno given that Node exists?
Looks like Deno can run .ts files without first compiling to .js. What are the other benefits?
Looks like Deno can run .ts files without first compiling to .js. What are the other benefits?
Deno is different than Node in several aspects; most notably:
- Deno supports only ES modules, there's no built-in support for CommonJS modules
- Deno's APIs are all promised based
- Deno does not use NPM, instead it can pull code from any URL, much like browsers do
- Deno has built-in permission system that by default runs your code in full sandbox allowing to opt-in into breaking out of sandbox (eg. to read a file from disk)
- As you've mention Deno can run .ts files without explicit build step
- Deno comes with a full toolchain in a single binary (formatter, linter, test runner, bundler, doc generator)
I've tried to get Deno to work before in production, but it had so many compatibility issues last I tried it would take weeks or months to refactor things so it would work.
I completely agree with that! But on the other hand with plethora of tools available it can be quite overwhelming to configure all the tools, especially for new users.
> I've tried to get Deno to work before in production, but it had so many compatibility issues last I tried it would take weeks or months to refactor things so it would work.
Work on compatibility layer with Node is ongoing [1]. With every release there's some new API being compatible, but far from over.
If you write a library, you need to support several export types for node packages. In your `package.json` you must include a `main` `module` and `exports` object and provide two compiled outputs, one commonjs and one es modules.
Then you need to worry about mutating import paths to include the file extension, which can cause trouble when you keep the commonjs and esmodule files in the same folder.
Also the esmodule loader in node doesn't have access to things like `__dirname`, so certain things can break.
not to mention node_modules...
It's like IE support but on the back end.
Then you step into the front end and it's another whole layer of chaos.
Give me opinionated compilers with minimal configuration and let me write code.
This is a hassle, but didn't used to be true for node - you could say the same as all the above for commonjs, wasn't it nice to have a single opinionated standard.
In the short term, deno avoids this by dropping backwards compat, great! But in the long term, I don't see how it doesn't end up in exactly the same place as soon as the next big change to JS modules comes out, or the next new build environment or wasm integration becomes bigger or...
Unless they have a fundamentally different strategy for the future (either 'we will never evolve' or 'we will evolve with ecosystem-wide breaking changes') they're going to end up in the same state as node today, eventually. I haven't seen any discussion of such a strategy at all. It's just a temporary reset - unlike node, they get to break backward compat and support the One True Format because they're new, that's all.
Nobody forces you to use the deno dev tools. You can still run eslint, prettier and closurescript, if that's your sort of thing.
Personally, I prefer deno lint over eslint and deno fmt over prettier since they are much faster. I'm even using dprint (which is a standalone project for code formatting, https://dprint.dev/) in Node projects.
Similarly, before deno test, I created my own deno testing tool. Now I use deno test instead since it's just better - not because anyone's forcing me to use it.
The integrated dev tools are a convenience feature. I hope that's kinda obvious.
Promises are very complicated compared to first class functions. What makes JS/Node hard to grasp is that it's async. Async is an (often unnecessary) optimization, with tradeoffs.
Loading modules from URL's is a cool concept! ES modules helps here, but you could also have a package-list file that lists all dependencies of dependencies as well as download mirrors, or hashes with peer-to-peer distribution.
A permission system is nice, modules should not have system access by default.
Not everyone wants to use TypeScript. It will probably become obsolete once optional type annotations gets added to JavaScript.
An opinionated toolchain is nice, but should be optional IMHO.
I'm not sure what you mean by "bad practices like include files" so I can't comment on that.
I've found most Javascript developers prefer the await syntax with promises to using callbacks. It gives the code the appearance of being synchronous with the ability to do things more asynchronously if you need. I haven't encountered many who actively prefer the callback style. It gets unruly fairly quickly.
I can't see optional type annotations ever being added to Javascript. They would have to be checked at runtime which isn't something I'd imagine browser vendors wanting to implement.
The feeling that I get is that the standards committee is trying to bring Javascript to be the best dynamic language it can be and if people want more comprehensive guarantees then there are excellent tools like Typescript which give that option.
The fact there have to be multiple implementations of the standard in the various JS runtimes makes it a hard sell to evolve Javascript too far.
Its in Typescript 3.8, Node 14.8 and probably in your Babel setup. I probably wont get to use Node 14 in prod for a while but I get by with a `main` function that has everything in that gets called at the bottom.
You don't have to use TS. Deno runs plain JS, too.
> [TypeScript] will probably become obsolete once optional type annotations gets added to JavaScript.
What makes you think that type annotations will be added to JS? I think it's far more likely that browsers and other runtimes will natively support TS as a separate language rather than JS evolving to become TS.
> An opinionated toolchain is nice, but should be optional IMHO.
It is optional. You don't have to run deno lint, deno fmt, deno test, etc. But at the same time, they are pretty good tools so you might want to try them.
It has already been tried with Dart. Dart was made because JS lacked a type system, preventing further optimisations. Support for Dart was added in Chrome.
Another popular JS transpiler is CoffeeScript, most of it's syntax is now in JavaScript.
Support for Dart in Chrome was added before Dart was popular (if you can even consider it popular at all). Since TypeScript is already popular now, I think if Chrome added support for stripping the types and running TS code as JS, most devs would welcome that.
That's not true any more, ES Modules have made it into the spec, so that's what Deno is using.
As for package-lists, the current convention in the community at the moment if you have a decently sized library is to have a `deps.ts` file where you re-export all of your dependency, making it an equivalent to package.json and helps with upgrading dependencies across a codebase.
TypeScript is already optional in Deno! it will run any .js file just fine, and you even skip the compilation part.