Add support for Babel 7

[kripod]

As of today, having a .babelrc file with the preset @babel/preset-env makes the documentation build command throw an error.

[tmcw]

Customarily I wait until projects are in stable release state to update to them (babel 7 is still a beta). That said, if anyone wants to help out and write a PR for this issue (or any other!) happy to review & merge.

[anthony-redFox]

I have tried to migrate on new babel version, but in babelify source hardcoded uses babel 6 version. it is blocking for us. waiting PR babel/babelify#255

[vihanb]

@anthony-redFox git+https://github.com/ylemkimon/babelify.git#master could be used instead of NPM package name in package.json until babelify is updated?

[ganapativs]

https://twitter.com/left_pad/status/1031700991186489344

[tmcw]

That's great news! Setting a reminder to check back on Friday and start a migration if it's landed.

Any update on this?

[vihanb]

@suparng-medallia I believe #1114 has some more info on progress related to the upgrade

[tmcw]

Sorry for the delay on this issue, folks - it's in my TODO to review, merge, and deploy documentation.js with babel 7 support this afternoon (PST), assuming everything goes according to plan.

[tmcw]

All right - documentation.js 9.0.0-alpha.0 is published to npm. Please try it out, and report back on any failures or successes! It uses Babel 7 across the board, thanks to hard work from @vicapow and folks!

[haggholm]

I’m having issues with the alpha due to Babel configuration—we use legacy decorators and the syntax

@foo
export default class Cls { /* ... */ }

This is not supported by the default Babel configuration, which demands that the export come before the decorators:

export default @foo class Cls { /* ... */ }

Thus, running documentation on our code causes a Babel error:

 Using the export keyword between a decorator and a class is not allowed. Please use `export @dec class` instead. (47:0)
{ SyntaxError: Using the export keyword between a decorator and a class is not allowed. Please use `export @dec class` instead. (47:0)
    at _class.raise (/shared/owl-devtools/node_modules/@babel/parser/lib/index.js:3939:15)
    at _class.parseDecorators (/shared/owl-devtools/node_modules/@babel/parser/lib/index.js:7304:14)
    at _class.parseStatement (/shared/owl-devtools/node_modules/@babel/parser/lib/index.js:7142:12)
    at _class.parseStatement (/shared/owl-devtools/node_modules/@babel/parser/lib/index.js:1902:57)
    at _class.parseBlockOrModuleBlockBody (/shared/owl-devtools/node_modules/@babel/parser/lib/index.js:7696:23)
    at _class.parseBlockBody (/shared/owl-devtools/node_modules/@babel/parser/lib/index.js:7683:10)
    at _class.parseTopLevel (/shared/owl-devtools/node_modules/@babel/parser/lib/index.js:7110:10)
    at _class.parse (/shared/owl-devtools/node_modules/@babel/parser/lib/index.js:8510:17)
    at Object.parse (/shared/owl-devtools/node_modules/@babel/parser/lib/index.js:10462:38)
    at parseToAst (/shared/owl-devtools/node_modules/documentation/lib/parsers/parse_to_ast.js:32:22)
    at parseJavaScript (/shared/owl-devtools/node_modules/documentation/lib/parsers/javascript.js:51:44)
    at /shared/owl-devtools/node_modules/documentation/lib/index.js:131:12
    at arrayMap (/shared/owl-devtools/node_modules/documentation/node_modules/lodash/lodash.js:639:23)
    at map (/shared/owl-devtools/node_modules/documentation/node_modules/lodash/lodash.js:9556:14)
    at Function.flatMap (/shared/owl-devtools/node_modules/documentation/node_modules/lodash/lodash.js:9259:26)
    at buildInternal (/shared/owl-devtools/node_modules/documentation/lib/index.js:118:31) pos: 1884, loc: Position { line: 47, column: 0 } }

It does not seem to be possible to pass any configuration to Babel via documentation (correct me if I’m wrong). I’m not an expert on Babel, but I presume that export/decorator order is not the only thing that might conceivably fail in this way, though in this case it seems to be an explicit setting:

documentation/src/parsers/parse_to_ast.js

Line 14 in 49c0f72

['decorators', { decoratorsBeforeExport: false }],

Might it be possible to read Babel config from the target directory, or at least pass customised options via documentation?