Standardise lazy requires

[jeddy3]

Which issue, if any, is this issue related to?

#2454

Is there anything in the PR that needs further explanation?

In this pull request, I've standardised how we lazy/dynamic-require:

• formatters
• rules
• syntaxes

Previously we were using lots of different workarounds to get the require-time down. I'm now only using import-lazy.

This lays the foundation for being able to bundle code, closing #2454 and #3935.

This pull request doesn't improve the require-time much, because we'd already optimised all that we could without bundling (using the various workarounds). Require-time does seem more consistent, though, normally coming in at the 120 mark.

This pull request does, however, improve the time taken to run stylelint when the auto syntax is used because all the syntaxes are now lazy-required.

Testing locally with

{
  "code": "a { color: #fff; }", // or sass equivalent
  "config": "{ rules: { "color-hex-length": "long" } }"
}

On master:

// no syntax
node test.js  0.44s user 0.14s system 0.651 total

// no syntax, sass file
node test.js  0.43s user 0.10s system 0.787 total

// syntax: “css”
node test.js  0.17s user 0.05s system 0.294 total

This branch:

// no syntax
node test.js  0.16s user 0.04s system 0.232 total

// no syntax, sass file
node test.js  0.19s user 0.04s system 0.221 total

// syntax: “css”
node test.js  0.16s user 0.04s system 0.200 total

Using the auto syntax is almost comparable to using the syntax option in this branch, whereas it's significantly slower in master.

This improvement is reflected in the test suite which now runs in 72s (down from 92s).

The import-lazy library has two patterns:

• standard
• for bundlers

I'm using the former for formatters and rules, and the latter for syntaxes. This will allow us to bundle syntaxes separately in the future.

As a consequence, it exposed a shortcoming in how we were excluding files from TypeScript. Previously all the rule files were ignored because they were excluded and dynamically required using require("rules" + rulename), which TypeScript couldn't resolve. As we are now using a lazy-require pattern it can resolve, we have to explicitly mark each rule file with a // @ts-nocheck. This is arguably cleaner as we were previously relying on a quirk of the TypeScript's module resolution. The include and exclude TypeScript config options are cleaner too now.

[hudochenkov]

Great job!

[m-allanson]

Can this be moved to types/global.d.ts?

[m-allanson]

Nice, looks good!

[jeddy3]

• Fixed: improved performance when auto syntax is used (#4729).