[WIP] eslint code hinting

[ghost]

I've tried to configure eslint rules, based on scripts/helper.js. Can use this for more accurate further settings.

[azerella]

Thanks @toxamiz! I'll review the linting rules over the next few days, looks like a really good start though. We should also be looking at tools like https://www.npmjs.com/package/husky for when commits are made and ideally everything is formatted automatically.

I'm a bit skeptical on whether eslint supports some of the rules that we use, if it does that's great but we'll still need a way to automatically format them

[ghost]

For first look there are some indent issues (or the base file have indent issues :) ) and there no base rule for UpperCamesCase for global functions const CreateDir = ( dir ) => {...}.
Eslint can be extended with custom rules, if there are few missing rules, we can try to make them (or try to find)

[azerella]

Looks good @toxamiz, some more feedback:

• Rename eslintconfigs/ to .eslint/
• Add a lint script for jQuery, something like: "lint:js": "eslint -c .eslint/jquery.json packages/*/src/js/jquery.js"

We need to make a conscious effort that the module.js and jquery.js files are IE8+ compliant.

Looking at a plugin like: https://www.npmjs.com/package/eslint-plugin-ie11 might be a suitable option, or at least inheriting some of the rules from this.

[azerella]

Suggested change

	'ecmaVersion': 5
	'ecmaVersion': 5

I'm not confident this supports IE8-11 rules

[ghost]

It just forbid to use es6 syntax e.g. let, const, etc

[ghost]

https://www.npmjs.com/package/eslint-plugin-ie11 might be a suitable option, or at least inheriting some of the rules from this.

I don't think it is what we need

I tried to use https://github.com/amilajack/eslint-plugin-compat which should lint the browser compatibility, but i doesn't work properly: allowing to use [].map on ie8 for example.

Btw, don't you think about to just require module.js and jquery.js to be written only with es5 features (which is supported by ie9+) or use babel transpile, and advise your component users to include es5-shim and DOM-shim if they need support of ie8?.

With es5 requirement we can use 'env': {'es6': false}, 'parserOptions': {'ecmaVersion': 5}

[azerella]

Closing this in favour of #710. We'll move this discussion over to #710 @toxamiz