ES5 transpiling

[sigfriedCub1990]

Issue #238: Older browsers support through ES5 transpiling and polyfills.

Changes

• Updated ruby gems, specially webpacker to 4.0 version.
• Updated .babelrc to use the newly version of babeljs and @babel/preset-env
• Updated node packages to use latest babeljs, @babel/preset-env and necessary plugins.
• Added core-js polyfills to webpack entry file.

Notes

• Please, take special care with the first bullet point above, since I'm not a ruby developer probably I broke something 🙁, if that's the case I'll gladly downgrade the packages and I'll only upgrade the webpacker since that's the only critical package to upgrade.

[jonasjabari]

Hey @sigfriedCub1990! Thanks for your work here so far. I actually would ask you not to change the gem versions and only focus on the javascript adjustments :) Just to limit the scope of this PR. We will update the gems in other specific PRs. Thanks!

[sigfriedCub1990]

No problems @jonasjabari, the only gem I really need to update is the webpacker gem

[pascalwengerter]

Hey @sigfriedCub1990 looks very good to me!

Just two things that should happen before we can merge - could you

• Merge the latest develop branch into your repo
• Delete your Gemfile.lock and only run bundle install? We'll do the upgrade stuff (Rails 6 et al.) in a separate branch :-)

[pascalwengerter]

Hey @sigfriedCub1990 thank you for the clarifications!

The thing with Gemfile.lock didn't turn out the way I hoped, though. Could you simply remove the file from your PR and I recreate it locally after merging your PR? :)

[pascalwengerter]

Hey @sigfriedCub1990, thank you for the fast reactions!

I've now checked out your changes locally and the tests suite passes, so we're fine on that side. In the vendor/assets/javascript/ however, there's still a number of const and let ES6 in the .js files that are created/updated by running ./bin/webpack in the builder/ directory.

Do you have an idea how to fix that? Or am I missing a step somewhere?

[sigfriedCub1990]

Hey @sigfriedCub1990, thank you for the fast reactions!

I've now checked out your changes locally and the tests suite passes, so we're fine on that side. In the vendor/assets/javascript/ however, there's still a number of const and let ES6 in the .js files that are created/updated by running ./bin/webpack in the builder/ directory.

Do you have an idea how to fix that? Or am I missing a step somewhere?

Let me check that after lunch :)

[sigfriedCub1990]

Hey @pascalwengerter, it seems like there is partial support in IE 11 for let and const declarations, so it shouldn't be a problem. More info here const, let.
Anyway, if we could test this with IE 11 users I would be more comfortable :) and if there's a problem I'll fix it.

[pascalwengerter]

@sigfriedCub1990 great work so far! We'll test the changes using browserstack and will let you know if IE does complain 😉