Don't use regenerator in babel-preset-es2015 for newer Node.js versions

[sindresorhus]

Split out of #333.

Only Node.js 0.10 needs regenerator, but it's currently included for any Node.js version.

Someone needs to do a pull request to babel-preset-es2015 and auto-detect generator support and conditionally include regenerator (preferred solution) or add an option for toggling regenerator.

// @thejameskyle @jamestalmage

[thedev]

What do you think about using a post install script ?
Noticed the following discussion: npm/npm#7340

[sindresorhus]

@thedev This isn't about having regenerator as a dependency. We just don't want the runtime overhead of using regenerator when it's not needed for newer Node.js versions which supports generators.

[jamiebuilds]

Someone needs to do a pull request to babel-preset-es2015 and auto-detect generator support and conditionally include regenerator (preferred solution) or add an option for toggling regenerator.

The Babel preset would not accept a pull request for that, just because the environment that is running Babel supports generators does not mean the targeted environment will.

If you want to create a preset babel-preset-node-feature-detection that tests for support for everything before running it, that would likely be the best solution. However, it should warn heavily that you should not distribute the generated code with it (we don't want npm filled with node version specific modules).

[sindresorhus]

@thejameskyle That's a good point. I just considered our case of live transpiling. Would you be open to add an option to the preset for toggling regenerator? We really don't want to have to maintain our own presets.

[jamiebuilds]

https://phabricator.babeljs.io/T2756

[ariporad]

@sindresorhus: Check out hax/babel-features. I'll turn it into a preset if you want. Or we could just use it directly.

[ariporad]

@sindresorhus: Actually, I went ahead and turned that into a preset anyway: babel-preset-features. It's a drop-in replacement for babel-preset-e2015, I'll submit a PR.

[tmaximini]

I ran into the same issue, went with https://github.com/alekseykulikov/babel-preset-es2015-node5 for now

[jamestalmage]

@tmaximini What issue? The only difference should be one of performance. If you've got other issues let us know.

[novemberborn]

Closing in favor of #148.

[buzinas]

@jamestalmage performance always matters, and it's always good to have as much as possible a generated code side-by-side with the source one.

If we have native support, we should always use it, there is absolutely no reason to use something ugly and gross on top of something that already exists and performs well.

I can understand people using bluebird instead of the native Promise, for example, but using a feature like regenerator, only if targeting browsers.

Another great difference: Debugging is terrible with regenerators, and it's awesome with native generators.