TypeScript: ES5 target support

[vguzev]

Is it possible to add TypeScript configuration with ES5 target?
We can't use getters/setters with current version of TypeScript 1.8.10...

For example when I try to run this kata
https://www.codewars.com/kata/590b85b745eaa415e10000b1/train/typescript
I'm getting errors:
../home/codewarrior/solution.ts(28,7): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.

In command line this can be done via command:
tsc task.ts -t ES5

[kazk]

This should be possible.
I think the target is supposed to be es6 already, but it's not working.
There's unused /runner/tsconfig.json with

{
  "compilerOptions": {
    "target": "es6",
    "module": "commonjs"
  }
}

---

@jhoffner
TypeScript support needs some fix and updates (#380).
As far as I know, using @types modules will allow us to remove all the TypeScript stuff at the root of the project. And @types will be included in compilation by default so /// comments can go away.
See the blog The Future of Declaration Files.

[jhoffner]

Sounds good. Would love to get this up-to-date. We will need to make sure to make /// backwards compatible if it isn't aren't already with 2.0.

[kazk]

...I didn't think about the compatibility issues with TypeScript 1.8 and 2.0+ :(
Maybe it's not as easy as I thought then. I don't know TypeScript much so I won't be able to do this anytime soon unless someone can let me know the requirements.

[jhoffner]

Maybe it's not as easy as I thought then

If we can support both 1.8 and 2.0 at the same time then we should be fine. I guess we could just manually copy the 1.8 files into the node_modules folder on the image (unless there is a better way to support two versions via npm).

[kazk]

docker/node.docker#L23-L24 installs the latest stable release and Codewars currently has v2.2.1.

# Install TypeScript
RUN npm -g install typescript

// Kumite
const cp = require('child_process');
console.log(cp.execSync('which tsc', {encoding:'utf8'}));
//=> /.npm-global/bin/tsc
console.log(cp.execSync('tsc -v', {encoding:'utf8'}));
//=> Version 2.2.1

[jhoffner]

Hmm, should have locked that to a version...

[vguzev]

The problem is not in version of typescript. You should use latest version of typescript on your servers.
But keep in mind that "tsc" is transpiler, i.e. it transforms programs, written in TypeScript to programs written in JavaScript. By default it transpiles to ES3. But as you know not all features are available in ES3. For example getters/setters are available only in ES5. I.e. you need some kind of configurations for TypeScript, so that you could tell tsc to generate JS code according to ES5 standard and then use javascript compiler that understands ES5 (for example Node v.6.6.0/Babel).

I want to say that there must be TypeScript analogue for this dialogue:

with options ES3, ES5, and etc...

[kazk]

@vguzev
That should be fixed by tsc --module commonjs --target ES6 in lib/runners/typescript.js#L46, if I'm not misunderstanding.

I was trying to cleanup the codebase while doing so.

[kazk]

Multiple targets can be done through opts.languageVersion and setting the default to ES3 shouldn't break existing ones.

[vguzev]

Have not idea what does that mean )
Here is the simple TypeScript snippet which can be compiled with ES5/ES6 targeting only, but not with ES3:

class A {
 get b() {
  return true;
 }
}

[kazk]

@vguzev
Sorry, maybe I should have opened a new issue.

I understand what this issue is about, and making -t/--target configurable shouldn't be hard to do. So I started to discuss how to proceed with this and also fix some existing issues. Using @types should resolve #380 and that's why the version became a concern. This issue is not affected.

[kazk]

I just re-read #380 and the issue is about Array.from not recognized which might be the same target issue and not outdated typings. Array.from was specified in ES2015/ES6.

[vguzev]

Perhaps switching the default target from ES3 to ES6 could be the workaround for now...?

[kazk]

We can make -t/--target configurable to one of "ES3", "ES5", "ES6"/"ES2015", "ES2016" (through opts.languageVersion) and set "ES3" as default for backward compatibility. This should allow users to select the target similar to JavaScript's language versions when necessary.

[vguzev]

Cool! That would be great! )

[kazk]

@jhoffner what do you think of making targets configurable as described above?
If you think this is valid approach, can you change the title to something like "TypeScript: Make target configurable" so it's easier to see the goal? Also maybe create TypeScript Epic and put this and #380 in it. For #380 and using @types, I think we should do it separately.

I won't be able to do it right now since my TODO list is getting long, but this one should be relatively easy.

[jhoffner]

If we were to use targets as language versions, we would probably want to do 1.8/ES5, 2.2/ES5, 2.2/ES6, etc.

I'm wondering if the accidental update from 1.8 to 2.2 caused any backwards compatibility issues with existing content. If it didn't, we could just leave it upgraded and not worry about 1.8 at all.

As far as ES5 vs ES6, I'm thinking it's probably safe to switch to using ES6 as the target without ES3/5 support at all. ES5 is in the past, lets leave it there.

[kazk]

Yeah, TypeScript's compatibility needs to be looked into.

For targets, I think the issue will be allowing sloppy mode or not. JavaScript (ECMAScript) is very careful with backward compatibility because of "don't break the web". I'm assuming the default target "ES3" is sloppy and "ES5+" is strict. So just keeping "ES3" and the latest standard might be enough.

I found a tsc option --noImplicitUseStrict. We might be able to just target the latest standard by using this?

[vguzev]

Hi! Any updates?
I started working on Typescript katas https://www.codewars.com/collections/learning-typescript and I need modern version of tsc compiler for some katas... (

[kazk]

@vguzev we won't be able to have this feature on Codewars anytime soon. There're some things we need to look into and decide. Also, @jhoffner will be on vacation starting tomorrow.

If you can provide information about any breaking changes between TypeScript 1.8 and 2.2, that'll help.
tsc is v2.2 by accident and we need to ensure v1.8 compatibility.

---

@jhoffner maybe #316 (Invalid 'reference' directive syntax.) is caused by the update?

[vguzev]

Oups... I meant not the "modern compiler", but configurable targets. The problem is that tsc v.2.2.1 also have ES3 target enabled by default. There is a PR out there microsoft/TypeScript#15466 for switching default target to ES5, but it is not available in current version of tsc.

[vguzev]

Meanwhile typescript 2.4.2 was published several days ago... any updates on this issue?

[kazk]

I guess we can forget about 1.8?
If so, we can have language versions 2.4/ES3 (default) and 2.4/ES6.
I'll open a PR.

[vguzev]

@kazk Great! Don't forget to set --target es6 as parameters, because by default es3 target will be set even with the new versions of compiler. See microsoft/TypeScript#10117

[kazk]

@vguzev see #476.
This implementation accepts any of the targets supported by tsc 2.4, but Codewars will probably only show few major ones like 2.4/ES3 and 2.4/ES6.
Let me know if I missed anything.

[vguzev]

@kazk Looks OK for me :)

[vguzev]

When will it be available on codewars.com? Currently I see only version 1.8.10 of typescript: