Docs: Difference between esnext, es6, es2015 module targets

[bcherny]

Search Terms

esnext, es6, es2015, module, tsconfig, tsconfig.json, difference, document

Suggestion

It would be great if this can be documented. On the face of it, the output for all three seems to be identical.

Related: It would also be nice to document why targeting module: "none" when your code is a module (ie. uses ES2015 imports/exports) generates CommonJS-compatible code instead of exporting to globals as "none" seems to imply.

[DanielRosenwasser]

To just answer the question, the difference is that import() expressions are understood in esnext, but not in es2015 (and as of TypeScript 2.9, import.meta is only understood with esnext).

I guess you could possibly expect an es2019 module target for both.

[mhegazy]

in addition to what @DanielRosenwasser mentioned, esNext is just a place holder for features that are on the standard track but is not in an official ES spec yet. e.g. import.meta and import() expressions. as TC39 adds these features to a versioned spec, we will add a new --module ES20** to reflect that.

Also es6 === es2015.

[qm3ster]

Is there a place where I can see the list of https://github.com/tc39/proposals syntax supported?
(As opposed to module target or libs.d.ts?)

[zoltan-nz]

You can find all the libs and supported features in this folder: https://github.com/Microsoft/TypeScript/tree/master/lib

[gilamran]

The only place that I found for understanding TS support is here, but this table is misleading... "red" doesn't mean that TS doesn't support the feature, it means that it doesn't run on previous version of JavaScript... yea, misleading.

Can we create a similar solution for TS, but with real supported/unsupported table? (With relation to the target)

[ayqy]

Is there someone who can give a detail explanation for module: "none" ?
ref: Difference between typescript module “None” and “CommonJS”

[vegerot]

Is targeting ESNext or module ESNext stable for long term releases? What if I want import() but also want stability?

[Mikilll94]

@vegerot
Any answer to this question?

[vegerot]

I wish

[DanielRosenwasser]

If you're looking for stability, you may want to hold off on using --target esnext unless you're piping the output through another compiler that supports newer ESNext syntax like Babel. If a feature is only available under ESNext, you'll likely need to wait until it is clear which version of the ECMAScript standard it will be added to.

[vegerot]

If, say the end result we send to users is ES2016 compatible (say, through Babel), does it make sense to target ES2016 and then pipe through the other compiler? Or to target ESNext and pipe it through the other compiler (assuming the other compiler supports ESNext)?

[DanielRosenwasser]

If you're targeting a minimally ES2016 environment (most modern browsers, most recent versions of Node) then there's no need to pipe through Babel except for auto-polyfills.

If you need auto-polyfilling, emit to ESNext and pipe through Babel.

If not, just emit to ES2016 with TypeScript.

[scarcoco]

tsconfig.json module options: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'，what's different of 'es2020', or 'ESNext'?

[stephen-dahl]

@scarcoco I am guessing from reading this that es2020 is when the import() and import.meta landed. I am just guessing though. ESNext is all the new features that have not been finalized yet. there may or may not be any difference between that and es2020 at the time of writing but in the future when more features are inevitably added to the module system ESNext would include those.

[thernstig]

Top-level await was included in ECMAScript 2022, see https://github.com/tc39/proposals/blob/main/finished-proposals.md

But there is no "module": "ES2022", so one is forced to use "module": "esnext". But next seems dangerous to me as in a few years from now it might mean new features we do not support yet due to not having upgraded Node.js.

It's not clear for me why there is no ES2022 to support top-level await without having to resort to next.

[bennycode]

I recently noticed that import assertions are supported with module esnext and nodenext, but not with es2022 (tested with TypeScript 5.1.6). I assume that is because ESNext is continuously evolving but ES2022 is not?

@thernstig it looks like "module": "es2022" will allow you now to use top-level await (tested with TypeScript 5.1.6):

Top-level ‘await’ expressions are only allowed when the ‘module’ option is set to ‘es2022’, ‘esnext’, ‘system’, or ‘nodenext’, and the ‘target’ option is set to ‘es2017’ or higher.

[RyanCavanaugh]

New module docs are live at https://www.typescriptlang.org/docs/handbook/2/modules.html

[catamphetamine]

New module docs are live at https://www.typescriptlang.org/docs/handbook/2/modules.html

I'd suggest the following link: https://www.typescriptlang.org/tsconfig#module

[mrdulin]

I'd suggest this docs: https://www.typescriptlang.org/docs/handbook/modules/theory.html#the-module-output-format