Update package.json with fesm2015

[prateekbh]

We should bundle both esm/es5 files in every package and expose them using fesm format

Spec details:
"Angular Package Format" on Google Docs

[cromefire]

Looks good, but points to discuss:

• Use tsickle to annotate code for closure
• es2015 or newer, because almost all browsers support that newer features (e.g. async functions)
• fesm vs. esm vs. both

[prateekbh]

Lets skip closure shall we? Its a huge hugeeee maintenance effort.

[cromefire]

tsickle is just a drop in typescript compiler, which handles that

[prateekbh]

Lets look at that but not make this a blocker for 2.0. Have had some bad experiences with closure compiler in past

[cromefire]

I would try it and if it doesn't work as a drop in, I would postpone it to after 2.0

[cromefire]

So can we agree on having only esm and es5?
What browsers should we support for es5?
I would say:

• Chrome: last 2 versions
• Firefox: last 2 versions
• Firefox ESM
• Safari: last 2 versions
• Edge: last version
• IE: ? version

[prateekbh]

Actually I was going for es5 and fesm(flat esm)
For es5:
Babel-preset-env: last 2 browsers and IE11
For FESM:
Babel-preset-env: esm

[prateekbh]

Or just use https://www.npmjs.com/package/babel-esm-plugin

[cromefire]

Actually I was going for es5 and fesm(flat esm)

Do you know a build system, that can handle fesm? I do not. And I don't know any advantage of fesm vs. esm

Babel-preset-env: esm

We should'n need babel at all

Or just use https://www.npmjs.com/package/babel-esm-plugin

But that's only for webpack

[prateekbh]

Esm uses native es modules but fesm does not.

Fesm are flattened modules, like from webpack.
No native modules but the transportation is targeted to es2015.

This means we don't have to support native modules but we can ship stuff like async await, classes and more of es6

[cromefire]

This means we don't have to support native modules but we can ship stuff like async await, classes and more of es6

We should definitely include the files in es module format, without that there is no tree-shaking and with es modules included in all modern browser and node.js it will definitely the future, also because it's the only standardized module system.

[cromefire]

Esm uses native es modules but fesm does not.

@prateekbh Reading the docs, they do use es modules, but there is no good build system, but export {[...]} from "[...]"; does work