Harmony support

[ozanmakes]

I'm trying to use the excellent livenode with a project which uses ES6 features introduced in node v11, but unfortunately UglifyJS's parser chokes when it encounters a let statement or a generator function (function *() { yield true }).

[kevyworks]

Any comment on this?

[mgol]

That would be great to have, ES6 brings a lot of important new features but minification of all of them is still needed.

[Martii]

+1

[maranomynet]

+1

[darky]

:+1:

[ben-eb]

+1

[kevinjalbert]

:+1: just got bit by for...of.

[ghost]

If harmony support were enabled, we could also safely convert functions that don't use this to use the => syntax as well.

[fabiosantoscode]

+1 -- I'm writing a game for future browsers so I don't want to add the overhead of traceur to my code.

I also think converting functions to arrows when this is not used would be pretty nice.

[fabiosantoscode]

Adding harmony support on my fork, https://github.com/fabiosantoscode/UglifyJS2/tree/harmony little by little, to later pull request that back to this project.

Got arrow functions working so far (I think).

[rvanvelzen]

@fabiosantoscode Awesome! It would be super cool if you could submit separate new language features as separate pull requests. That will make reviewing them a lot easier. :)

[fabiosantoscode]

Okay, I'll restructure my commit history to do just that.

I'm writing some tests for the parser, and am thinking of doing so for the output as well, is that okay?

[rvanvelzen]

That is certainly okay! Related tasks: #337, #410.

[19h]

:+1: bump.

[simonzack]

:+1:

[RamIdeas]

:+1:

[lewispham]

:+1:

[avdg]

I hope everyone knows how to find technical information about ecmascript 6 / ecmascript 2015

Some examples:

• Candidate specs: http://wiki.ecmascript.org/doku.php?id=harmony:specification_drafts
• Es discuss: https://esdiscuss.org/

Note: understanding the structure of the spec, instead of reading it may be more important long term, so its easy to find information about specific items of the spec.

Good luck

[niemyjski]

+1

[f0rmat1k]

:+1:

[RevanProdigalKnight]

:+1:

[dgieselaar]

Please, everyone, don't comment with a 👍 or a +1: they add nothing to the discussion and will only antagonize people who have expressed their interest The Right Way™: with the subscribe button.

[darky]

Like most clearly expressed priority of issue You can even sort by "Most commented"

[Martii]

@plestik Adding a vote for support is always in the best interest of a project and is how it has been done for decades. ES6 syntax is something that this project should support to maintain high standards of quality. I am also subscribed to this thread. As you can see by the community outreach there is a strong interest and it should be taken seriously not complained about. :)

[avdg]

Maybe we should start with this question as we can all learn things from each other:

What is your favorite es6 feature?

[avdg]

Those who want to experiment with es6 can do it here: https://iojs.org/en/es6.html

It's basically a fork of node with many es6 features enabled by default.

[Martii]

What is your favorite es6 feature?

Block level scoping with let statement versus var is a plus. This is the most common entry syntax for ES6.

[RevanProdigalKnight]

I have to agree with @Martii; let will be a huge plus for temporary loop variables.

[art-in]

What is your favorite es6 feature?

generators ftw! co + generators + promises ♡

[darky]

@artin-phares Awesome!

[avetisk]

:+1:

[albertorestifo]

:+1:

[arackaf]

I'm curious if there's some sort of status page tracking which ES6 features are yet implemented. Like this, over at Esprima.

https://github.com/jquery/esprima/issues/1099

[sbrl]

That would be handy not only for the UglifyJS developers, but also for other developers who use this library to minify their code.

On 13/07/2015 02:33am, arackaf wrote:

I'm curious if there's some sort of status page tracking which ES6 features are yet implemented. Like this, over at Esprima.

jquery/esprima#1099 https://github.com/jquery/esprima/issues/1099

— Reply to this email directly or view it on GitHub https://github.com/mishoo/UglifyJS2/issues/448#issuecomment-120780583.

[rbozan]

+1.. At least add the let and const tags as they should act the same as "var", and in the future you could make the let tag name change on every block

[Martii]

Note ECMAScript 6th Edition (ES6 a.k.a Harmony) was finalized relatively recently last month.

See also:

• http://ecma-international.org/ecma-262/6.0/

[SET001]

What is your favorite es6 feature?

Please add support for classes and let!

[rbozan]

By the way for anybody reading this, just use Babel.io before you use Uglify, it would work

[mgol]

use Babel.io before you use Uglify, it would work

This prevents browsers from using their own optimized ES6 implementations; over time it will get faster than transpiled ES5 output. Also, this forces even good, modern browsers to download a lot of polyfills.

ES6 support in a JavaScript minifier is needed. It will get more & more needed in the future.

[probins]

also, some ES6 code, like arrow functions, is more concise than ES5, so a modern minifier should be converting ES5 to ES6 for optimal compression

[fabiosantoscode]

@probins I started work on that, but it currently depends on my pull request for arrow functions being accepted.

[rvanvelzen]

I started work on that, but it currently depends on my pull request for arrow functions being accepted.

Could you point me to that PR? I can't seem to find it?

[fabiosantoscode]

I didn't create it yet after all, it was dependent on whether my other pull request was accepted. I'll send it soon

[rbozan]

@mzgol Atleast it works for now, I don't really see this feature getting added to Uglify soon

[g-ortuno]

@rvanvelzen when is the next release planned? Can't wait to use arrow functions with uglify :smile:

[fabiosantoscode]

It would be great to see "beta" support of ES6 coming out so people can report any issues in our implementation of it before we finish all the features.

[g-ortuno]

@fabiosantoscode +1

[84564221]

See UglifyJS2/tree/harmony

[lewispham]

@fabiosantoscode Do you have any list of anticipated features?

[sbrl]

@fabiosantoscode Beta releases sound good. I think that the github release system lets you mark a release as a pre-release - perhaps that would work?