Vue: Provide ES2015 bundle?

[myst729]

What problem does this feature solve?

Recently I'm working on a project that attempts to deploy ES2015 code to production. The idea was inspired by Philip Walton's post.

I hacked vuejs-templates/webpack to output dual bundles with feature detection to downgrade. The benefit is significant: ES2015 script execution time is only about 55% of ES5! And the bundle size reduces too. If vue (as well as vue-router, vuex, etc.) could provide ES2015 bundles, the performance boost can be even more significant.

According to the es6 compatibility table, ES2015 compatible browsers have got a lot of market shares. Although vue relies on ES5 feature Object.defineProperty, I think it is still meaningful to provide ES2015 bundle as an option.

What does the proposed API look like?

This request is not about some particular APIs.

[felixbuenemann]

I believe PR #7110 tackles this issue.

[felixbuenemann]

To clarify: The ESM build also disables buble ES6 to ES5 transpilation in addition to allowing direct import in the browser as a module.