STR: 1. Plug in your device, I'm using Flame 2. cd gaia; DEVICE_DEBUG=1 make production 3. Launch WebIDE from Firefox Nightly 4. Open app vertical Homescreen, and select the file "gaia_build_defer_index.js", you'll find the JS is not prettified and from Firefox Nightly thre's an exception: Stack: SourceActor.prototype._sendToPrettyPrintWorker/</onReply@resource://gre/modules/commonjs/toolkit/loader.js -> resource://gre/modules/devtools/server/actors/script.js:2907:27 Line: 2907, column: 26 togglePrettyPrint threw an exception: Error: Unexpected character '`' (421:499) raise@resource://gre/modules/devtools/acorn/acorn.js:231:15 readToken@resource://gre/modules/devtools/acorn/acorn.js:738:7 getToken@resource://gre/modules/devtools/acorn/acorn.js:146:7 prettyFast@resource://gre/modules/devtools/pretty-fast.js:777:15 self.onmessage@resource://gre/modules/devtools/server/actors/pretty-print-worker.js:37:24 The backtick is from here: http://lxr.mozilla.org/gaia/source/shared/elements/gaia_grid/script.js#237

Probably we need an upgrade of acorn, it is now v0.9.1 but we have v0.4.1.

I believe this is not specific to WebIDE, as there is one pretty print path. Nick, do we need an upgrade, or how would we handle this?

The pretty printer only supports ES5 due to acorn only supporting ES5.

Nick, as I already wrote in other topics, ES6 support landed to Acorn few months ago.

Ok, well then someone can go ahead and update our checkout of acorn and update pretty-fast to pretty print ES6 forms. I'm happy to review these patches/PRs.

I just tried v0.9.1 and set defaultOptions.ecmaVersion 6, but it does not resolve the issue. There comes another exception: togglePrettyPrint threw an exception: Error: Unexpected character '@' (422:4) raise@resource://gre/modules/devtools/acorn/acorn.js:329:15 readToken@resource://gre/modules/devtools/acorn/acorn.js:912:7 getToken@resource://gre/modules/devtools/acorn/acorn.js:222:7 prettyFast@resource://gre/modules/devtools/pretty-fast.js:777:15 self.onmessage@resource://gre/modules/devtools/server/actors/pretty-print-worker.js:37:24 Which '@' is in http://lxr.mozilla.org/gaia/source/shared/elements/gaia_grid/script.js#238.

Have no idea what is this "@import". Probably internal feature of Mozilla's fork of Acorn or smth.

Ah, it's inside backtick. Well, I just checked with latest acorn and it parses fine for me.

I just tested with the latest acorn (51bc64a5), but still failed the tokenizing. I created an issue with the code for reproducing: https://github.com/marijnh/acorn/issues/169.

cc alex because this is about WebIDE.

RReverser proposed a solution [1] that tokenizer to return token literals as regular string tokens, as acorn seems is used for beautifying code only. But I am not really sure is this true, can someone please double confirm? [1] https://github.com/marijnh/acorn/issues/169#issuecomment-65766258

BTW, running |$ npm test| after set default option ecmaVersion 6 has some failed test cases (acorn v0.9.1): Normal parser: 843 tests run in 57ms; 20 failures. Loose parser: 815 tests run in 63ms; 1 failures. Total: 1658 tests run in 120ms; 21 failures. According to toolkit/devtools/acorn/UPGRADING.md, seems this is not ok to upgrade.

You shouldn't expect it to pass tests with `ecmaScript: 6` by default as some tests are specifically designed to check that some instructions **shouldn't** work in ES5 and those tests just have no `ecmaScript` specified, so they fail with different defaults.

(In reply to Ting-Yu Chou [:ting] from comment #11) > acorn seems is used for beautifying code only. But > I am not really sure is this true, can someone please double confirm? We use it in two places primarily: 1) Our pretty printer, which uses just the tokenizer. 2) We also use Marijn's tern.js for autocomplete-y stuff in the scratchpad. I believe this makes use of acorn's loose parser, but I haven't read tern's code or really looked at how we use tern, yet.

Tern is currently ES5-only, and will ignore ES6 syntax. (This will hopefully change in the future -- I'm looking for someone to hire me to work on it, maybe you can get Moz to do that?)

(In reply to Marijn Haverbeke from comment #15) > Tern is currently ES5-only, and will ignore ES6 syntax. (This will hopefully > change in the future -- I'm looking for someone to hire me to work on it, > maybe you can get Moz to do that?) Needinfo'ing dcamp on this because this should probably be his call.

I also just noticed that we already have a bug for supporting ES6 syntax in our pretty printer. Marking this as a duplicate.