Implements xo

[Chen3018]

xo is a configurable ESLint wrapper. That means its a linter and style enforcer. It includes plugins for ESLint like unicorn, import, ava, n and more. It also caches results to improve performance, which is important for a large codebase like Nodebb. No configurations are needed to begin using it.

xo run partial output:
xo-output.txt

Screenshot of xo run:

xo takes a lot longer than ESLint due to the fact that it does what ESLint does plus more. However, due to xo being highly customizable, run time can be reduced simply by excluding unnecessary/unhelpful rules (like 8 indents instead of 4). This also means we can also add plugins we think are helpful without much effort, as well as custom rules. The auto fixer is also extremely useful, reducing 127414 to 17779 (86% improvement).

xo can simply replace ESLint since everything done by ESLint is done by xo.

[coveralls]

Pull Request Test Coverage Report for Build 8290966844

Details

• 17 of 218 (7.8%) changed or added relevant lines in 5 files are covered.
• 38 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-76.3%) to 8.864%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/database/index.js	2	12	16.67%
public/src/modules/slugify.js	12	24	50.0%
src/meta/index.js	1	20	5.0%
src/pubsub.js	1	32	3.13%
src/meta/configs.js	1	130	0.77%

Files with Coverage Reduction	New Missed Lines	%
src/database/index.js	4	19.44%
src/meta/index.js	16	14.29%
src/meta/configs.js	18	1.56%

Totals
Change from base Build 8251971259:	-76.3%
Covered Lines:	35
Relevant Lines:	274

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💛 - Coveralls

[cathyxfeiyang]

included in CI pipeline (shown in failing lint checks - Run standard)