Switch to 6to5

[mourner]

https://github.com/mapbox/mapbox-gl-online/issues/558 — we should probably do this here too.

[tmcw]

👍 this should be easy, will do now.

[jamiebuilds]

Hey @mourner and @tmcw, contributor to 6to5 here. If you need any help with this feel free to stop by our gitter room.

[mourner]

@thejameskyle sure, thanks for the friendly note :)

[tmcw]

As discussed with @jfirebaugh, we're weighing pros/cons of switching back to es5 until io.js is a thing - tracebacks from es6 code running under node haven't been very accurate.

[jfirebaugh]

Yeah, going to revert to es5. Tooling support for es6 in node is too premature.

[jfirebaugh]

Also, to answer "why not io.js" -- it doesn't yet support the ES6 features we use (arrow functions and object literal extensions).

[mourner]

Yes, sounds good.

[jfirebaugh]

Recording for posterity the reasons to switch back:

• There are no node debuggers that understand source maps, so breakpoints etc. don't work correctly.
• Couldn't get istanbul to work under traceur or 6to5.

[jamiebuilds]

Couldn't get istanbul to work under traceur or 6to5.

You can use isparta as your instrumentor and it should work fine.

[mourner]

@jfirebaugh just wondering, did you try https://github.com/evanw/node-source-map-support?

[jfirebaugh]

Yes. It's only for exception stack traces though, doesn't help with debugging or code coverage.