Why would flow + es6 be better?
- When typescript came out, I was an early adopter, and a lot of it's touted benefits were the class-like syntax and constructors to make it more palatable to enterprise shops (not for me, but it was easier to sell to higher ups), this is mostly a moot point now.
- flow can be attached to any codebase as the codebase stands easily. It is, I have found, difficult to bring TS into an existing project.
- flow fits nicely into existing popular js tooling, mainly babel and react.
- no risk of vendor lock in. Maybe TS compiles to pure 100% syntactically correct javascript today, maybe it doesn't in the future. It isn't javascript, so I won't know.
> - You are writing javascript, not typescript.
Flow's and TypeScript's distance to JS world are the same, and are very similar in most cases. If you want to add type to one, it's the same as in the other. The only difference here is the file extension, since TS tends to like .ts/.tsx.
> - When typescript came out, I was an early adopter, and a lot of it's touted benefits were the class-like syntax and constructors to make it more palatable to enterprise shops (not for me, but it was easier to sell to higher ups), this is mostly a moot point now.
True, although IMO the greatest feature of TS is making your code stronger, not compiling things that are already part of some ECMAScript version.
>- flow can be attached to any codebase as the codebase stands easily. It is, I have found, difficult to bring TS into an existing project.
True, with TS it's more of a lateral move rather than drops here and there.
>- flow fits nicely into existing popular js tooling, mainly babel and react.
TS works just as well; better, IMO, because dev tools (editors, linters) have better TS support in my experience. Writing React in JS to me makes me feel like I'm using Notepad since there's so much TS helps me with that is lost when using a purely dynamic language.
>- no risk of vendor lock in. Maybe TS compiles to pure 100% syntactically correct javascript today, maybe it doesn't in the future. It isn't javascript, so I won't know.
It does compile to pure JS so ejecting TS is easy; it's trying to follow future standards and proposed changes, not create something different; the project is open source. There is no vendor lock in.
And it's worth noting that TypeScript having its own parser vs the rest of the world using Babel is a pain in the rear. See the time it took for ESLint (having to us TSLint in the meantime), now Prettier, having to use TypeScript with an ES6 target and piping the output in Babel to get proper plugin support, the difference between webpack's resolution mechanism and the one used by TypeScript in tools (an issue Flow also shares), and so on.
Some features like enums (omg, TS enums die die die) namespaces, decorators, and the old module system are also pretty awkward when blending with modern javascript. Makes you want to add lint rules to prevent them from being used.
Where the plugins shine is when compiling those (part of the standard) features to something interesting for production. Better inlining, adding debugging and instrumentation, compiling away certain things, optimizing your views for performance, etc.
All things that don't change the language whatsoever, but can improve your debugging or production experience.
That can be done in TS world (and is quite common) by targeting ES6 and piping the result in Babel though. It's just annoying.
You do have things like Prettier not being compatible with TS because different parsers, though.
It's our intention as a tool to align with TC39 and transition users to using native JS when it's supported
Honestly this is the main thing keeping me from using TypeScript. I've spent hours, maybe days trying to deal with the mess of Babel/webpack/TS combined with ES6 modules (necessary for tree shaking).
Another problem I ran into was using various packages that weren't typed, but I suppose I can solve that by 'allowing' implicitAny.
I'd really love some advice on this because I want to use TypeScript. It's just been a major headache so far because things are complicated enough with all the other moving parts (Babel presets, import vs require, better but still not well documented Webpack 2, etc.).
You can keep noImplicitAny and any-type just specific packages that can't/won't be typed. The declaration is now as simple as:
declare module 'path/to/module-name'
It's open source.
> you can just strip all type annotations with Babel and move on.
Are you implying that this isn't possible with TypeScript?
I think you're vastly misinterpreting what TS is.
It's not anything like CoffeeScript. It's JS plus types and a few other features like Interfaces or advanced ECMAScript features when targetting older versions of the standard.
If you strip away types by exporting to your ECMAScript target of choice, you'll get real JavaScript with the same style as it was written in TypeScript.
It's exactly the same thing you'd get with Flow in that sense. The only additional code you'd get would be for polyfills, but a) those are minimal and b) those will only appear if you export to an older ECMAScript version than the one you wrote it in.
There is no vendor lock.
That's about it though.
If you target ES6 your code may look identical. Even much of the ES5 down leveling produced code that looks like a person wrote it.
I converted a 10k line coffeescript project(with async/await !) to JS and then TypeScript. The similarities are so far apart they might as well be in different dimensions. But, if you don't want to take a rando posters word for it, it's pretty easy to make a little sample project and see if the output is to your liking.
The same can be done to it that would be done to Flow: you can just either strip types manually, or just do a single export to your ECMAScripttarget of choice. It'll be native JavaScript. Even the little shims/polyfills it does (to support older ECMAScript versions if you wish to export to it) are optional and can be disabled.
https://github.com/Microsoft/TypeScript/wiki/JSDoc-support-i...
It does a decent enough job at return types, but not a whole lot beyond that.
function double(x) {
return x * 2;
}
const result = double("foo");