Support ECMAScript versions as `targets`?

[rauschma]

I’m not sure how much that would be used in practice, but for some experiments and tests, it would be nice if one could specify an ES version to target.

Examples:

"targets": { "ecmascript": "2015" }
"targets": { "ecmascript": "5" }

[chicoxyzzy]

There are babel-preset-es* presets for that. Also babel-preset-env will never know what does "targets": { "ecmascript": "2017" } mean. Should it also add babel-preset-es2016, babel-preset-es2015, etc. or does target environment already support ES2016 and ES2015 so it needs just ES2017?

[rtsao]

There are babel-preset-es* presets for that.

IIRC these won't be created for future versions in favor of this preset. So for that reason I think supporting language targets make sense.

[AntJanus]

@chicoxyzzy I think if you specify targets: { "ecmascript": "5" }, you're compiling everything above it to the target. That's pretty straightforward. TypeScript does the same thing.

[xtuc]

This could be a good replacement for babel-preset-es*.

I think that { escmascript: es2016 } shoud include babel-preset-es2016, babel-preset-es2015.

I would prefer the es2015 format rather than the es6 one.

[chicoxyzzy]

Why should it include es2015 when that's not specified explicitly?

[rauschma]

My understanding would be:

• { "ecmascript": "5" }: the browser supports only ES5 or older. Transpile any newer features to ES5.
  • Same as babel-preset-latest.
• { "ecmascript": "2015" }: the browser supports ES2015 or older. Transpile any newer features to ES6.
  • Roughly similar to including all babel-preset-* except babel-preset-es2015 (which the browser already knows).
• Etc.

[AntJanus]

I think that makes the most sense. Like I said, it's what TypeScript does: you specify a compile target. A compile target of "ES5" means you're compiling down to ES5. ES2015 means you compile down to ES2015, etc.

[b-zee]

I think #234 and #264 are related.

In version 1 there is the uglify option, which will, according to the documentation, transpile down to ES5. Version 2 opts for a forceAllTransforms, which should do the same thing. However, those options don't directly make it clear it's about transpiling it to ES5.

Your solution seems the ultimate solution and is unambiguous in what result it would yield. Just like TypeScript (see www.typescriptslang.org/...) offers a target option, this package should too.

[babel-bot]

This issue has been moved to babel/babel#6613.