chore: use standard linter locally

[erickzhao]

Hi there,

I saw that the build on this project was failing due to code style issues, but there was no way to check the linting status beyond running on the CI or having standard installed globally.

I installed ESLint as a dev dependency (with the StandardJS preset) to make it easier to lint locally. npm run lint now detects errors locally. Since that command is now available, I added the local linter to the CI.

I also fixed a bug with TravisCI where the config ran on Node 6, which is no longer supported by core nor StandardJS. I replaced it with the latest LTS version of Node.

[yan-foto]

Thanks for the pull request.

"ESLint or Standard" is one of those ongoing struggles (like "vim vs nano vs emacs") that seems to remain unresolved for all eternity! That being said, I see no advantages in using eslint over standard. If the only problem is "having to install standard globally", you could solve it the same way that you did with eslint, namely by putting standard in the devDependencies and executing it as a node scricpt in package.json, i.e.:

"scripts": {
  "lint": "standard main.js"
}

and run node run lint.

I like the other changes that you made, so I'll keep this PR open, but I'd replace eslint with standard both in devDependencies and scripts. What do you reckon?

[erickzhao]

@yan-foto Yeah, using ESLint with the StandardJS preset instead of the standard package directly doesn't have direct benefits on the code, since it ends up being the same linting rules. I could definitely change this PR to use standard directly instead.

[yan-foto]

I'd really appreciate it if you would 🙏

[erickzhao]

@yan-foto done! :)

[yan-foto]

Great! Thanks again. I'll merge this into develop first, increase version number and merge with master.