Feature: Add babel transpiling to be backwards compatible with older Node.js versions

[bluzi]

Hi,

As we discussed, this PR adds Babel transpilation to the project.
From now on, you're going to have to run npm run build before you deploy a new version to npm. This will create a backward-compatible version of index.js in dist/.

Before merging this, there's something we still need to figure out together:
The listing files fail if the filespattern is empty test fails when executed against the transpiled code. I think it's because Babel ignores bluebird and uses its own Promise, but I'm not completely sure.
Anyway, I thought it will be best it I'll show it to you and make sure it's alright.

This is a complete list of what this PR adds:

• Few Babel dependencies to devDependencies (babel-cli, babel-core, babel-polyfill, babel-preset-env)
• .babelrc file
• The source file has moved to src/ (just to separate it completely from dist/)
• dist/ added to .gitignore
• I added build script to package.json

I've tested it using both Node v4.8.4 and Node v8.6.0 using this code, and it seems to work flawlessly.

LMK if you want any changes.

[lirantal]

Thanks for jumping on this. I appreciate the elaborate explanation and the work on the PR!

Remaining items for us to sort out:

1. If we need to ship a transpiled version for older Node.js then we need to ship dist/ with the npm package and remove it from git ignore, right? (or were you think we build it again on when it gets installed in the user's end?)
2. As you mentioned, we indeed need to remember running the build script before publishing, but thanks to npm elaborate life-cycle scripts we can use the prepublish run script to do that (see npm-scripts). Since we're testing with the transpiled code as the target, it also makes sense that before tests are run we build, so it requires updating the test script to also build before executing tests.
3. The problem is actually with the tests code itself. In const filesObj = myLicenses.fetch() filesObj is actually a promise object and we really need to async/await the result for myLicenses.fetch() because we're immediately checking the returned object. The pattern of not awaiting it worked in other tests because we were hooking into the events. In summary, the required change to fix it is really to update the function signature to be async and change that line to read const filesObj = await myLicenses.fetch()
4. Lastly, since we're using standardjs, can you please update /src/index.js to remove the semicolon from the require at the top?

Great job! I think that's mostly it.
Could you make the above changes on the PR?

[bluzi]

Hi @lirantal, it was my pleasure :)
Thanks for your comments, I fixed everything and now all the tests pass.

Travis still seems to be unhappy, but I don't see why. Any idea?

[lirantal]

great stuff!
minor change before we merge

[lirantal]

@bluzi we should use && between the commands instead of ; so that the 2nd part is only run if the first part is successful. can you make the change across the other commands as well? (test:watch, etc)

[bluzi]

Done

LMK if there's anything else :)

[lirantal]

One last change - since you moved the index.js file and we're also babeling it, then the current pointer to the root index.js file in package.json's main field needs to be updated.

[lirantal]

To be clear and elaborate on the above comment, you need to make the following change in package.json: "main": "dist/index.js"

[bluzi]

Yup, I understood :) one sec

[lirantal]

Cool. Sorry for the churn, I noticed it just now :)

[bluzi]

np :)

[lirantal]

Amazing job! 💪
Thanks for being so patient and prompt and of course for contributing this!

[lirantal]

@bluzi some open items we have for additional work:

1. Update the project with a proper travis ci file to run the tests (this is a good place to also check several Node.js versions so we can track when it breaks)
2. Updating the README for proper docs on the supported Node.js versions
3. There's a sister CLI project called https://travis-ci.org/lirantal/licenseye if you want to make the same babel support

I can open separate issues for each so we can tackle them in parallel PRs.

[bluzi]

Sure, open an issue for everything you want to add, and I might take one or two :)
Consider adding the #hacktoberfest label. It's a good way to attract new contributors nowadays.

Anyway, that was fun and productive :)

[lirantal]

oh right! great idea, I'll adopt it here and in my other repos too.

[bluzi]

Prepare to be overwhelmed with PRs :P

[lirantal]

Wouldn't take it any other way :-)