ES6 support?

[JRaspass]

UglifyJS2 supports a subset of ES6 in their harmony branch, they make releases of both the regular version and the harmony version in sync - https://github.com/mishoo/UglifyJS2/releases

Would it be possible to either switch to this harmony release or perhaps import both and allow people to pass a flag? This grunt plugin did something very similar - https://github.com/gruntjs/grunt-contrib-uglify/issues/393

[lautis]

As the UglifyJS releases seem to be now followed with a Harmony release, it could work to include both versions. I did few prerelease versions of Uglifier with the Harmony branch. Only very minor changes seemed to be necessary: https://github.com/lautis/uglifier/commit/8744268a8c46fcef19eeace51e49d911339e4edf.

[lautis]

@JRaspass I've implemented this in https://github.com/lautis/uglifier/pull/117. Would you be interested to test?

[JRaspass]

@lautis #117 worked beautifully for me, I replaced this line in my Gemfile:

-gem 'uglifier'
+gem 'uglifier', :git => 'https://github.com/lautis/uglifier.git', :ref => '9abd18da4f5eb2fb4b5aab8023f08470221743c1'

And then passed :harmony => true and it all worked, I used to get errors like this for arrow syntax:

JS_Parse_Error.get ((execjs):3538:621): SyntaxError: Unexpected token: operator (>) (ExecJS::RuntimeError)

[lautis]

Cool! I'll likely release that during the weekend.

[JRaspass]

Thanks :+1:

[lautis]

Released 3.2.0

[1c7]

the ES6 problem waste my entire afternoon to get fix.

    setTimeout(() => {
      jQuery('#app').addClass('event_open');
    }, 1000);

change to

    setTimeout(function(){
      jQuery('#app').addClass('event_open');
    }, 1000);

problem solved.

the things is this code along with other thousands line of code, that's why I didn't notice it for a long time. then suddenly I saw the() => {) syntax there, I know that's ES6 syntax. change it, and fixed!

Env

using Rails 5 and gem 'uglifier', '~> 3.2'

[nickrivadeneira]

For anyone else who stumbles on this looking to make ES6 work for Rails 5.1 and Heroku deployments, this change worked for me in config/environments/production.rb:

config.assets.js_compressor = :uglifier

becomes

config.assets.js_compressor = Uglifier.new(harmony: true)