Edge 14 doesn't get block scoping detected

[mgol]

Edge 14 passes all tests in the Kangax ES6 table in the const & let sections:
http://kangax.github.io/compat-table/es6/

However, specifying Edge >= 14 as a target still transpiles const to var:
https://babeljs.io/repl/#?babili=false&evaluate=true&lineWrap=false&presets=env&targets=&browsers=Edge%20%3E%3D%2014&builtIns=false&experimental=false&loose=false&spec=false&playground=false&code=const%20x%20%3D%202%3B%0A

I've looked at the code base. This is what I found:

1. Edge is not included in the list of environments that don't require the es2015-block-scoping transform: https://github.com/babel/babel-preset-env/blob/v1.2.1/data/plugins.json#L20-L27
2. The es2015-block-scoping transform seems to rely only on the results of const & let tests if I undersdand the code correctly: https://github.com/babel/babel-preset-env/blob/v1.2.1/data/plugin-features.js#L13-L18

It seems to me all conditions for Edge 14 to be accepted should be met?

[existentialism]

@mgol probably an issue where we're not assuming edge >= 12 includes everything from ie 11, and the compat-table data only lists ie11 under const/let, we'll get a fix out!

[mgol]

I was thinking that might have been the case but IE 11 doesn't pass all const/let-related tests so it's not included under transform-es2015-block-scoping either.

[mgol]

Oh, you mean that some tests under const/let are passed by IE 11 so the edge key is not included there while other tests are only passed by Edge.

That would mean Edge is not listed under anything that was partially (but not fully) supported in IE 11. That seems to be the case, indeed, as e.g. Edge is missing from es6.map: https://github.com/babel/babel-preset-env/blob/v1.2.1/data/built-ins.json#L102-L109.

[existentialism]

Yeah, we need to augment our checks to include previous browser(s) in the same family (ex. Chakra).

[mgol]

For reference, this is relevant upstream compat-table code taking the family into account:
https://github.com/kangax/compat-table/blob/e2a18bec5a4d951e749ad1cac848eade03d98c87/build.js#L431

[hzoo]

If you have time to check this out it would be great @mgol

All the code to generate the json files are in https://github.com/babel/babel-preset-env/blob/master/scripts/build-data.js. Maybe we need to redo #86?

[mgol]

I can look into it.

[existentialism]

Released in https://github.com/babel/babel-preset-env/releases/tag/v1.2.2!