Audit ESLint rules. I got 99 problems, but they seem to be JSDoc themed.

[pdehaan]

Was trying to find some ESLint errors in Circle-CI logs for a recent PR and noticed we currently have aboot 133 warnings.

npm run lint:js
…
✖ 133 problems (0 errors, 133 warnings)
  0 errors and 1 warning potentially fixable with the `--fix` option.

A bit of ugly grep-ing shows that about 99/133 of the warnings are jsdoc/* related.

npm run lint:js | grep -E "\sjsdoc/.*$" | wc -l # 99

We should probably either fix or mute those warnings, since it makes finding errors amongst the noise needlessly difficult.

As for the remaining warnings:

npm run lint:js | grep " warning " | grep -Ev "\sjsdoc/.*$"

LOC	TYPE	MESSAGE	RULE
152:23	warning	's' is defined but never used. Allowed unused args must match /^_/u	no-unused-vars
152:23	warning	's' is defined but never used	@typescript-eslint/no-unused-vars
7:10	warning	'UserInputError' is defined but never used. Allowed unused vars must match /^_/u	no-unused-vars
7:10	warning	'UserInputError' is defined but never used	@typescript-eslint/no-unused-vars
69:9	warning	Unexpected any. Specify a different type	@typescript-eslint/no-explicit-any
3:1	warning	header should be a block comment	header/header
12:49	warning	'page' is defined but never used. Allowed unused args must match /^_/u	no-unused-vars
12:49	warning	'page' is defined but never used	@typescript-eslint/no-unused-vars
10:44	warning	'res' is defined but never used. Allowed unused args must match /^_/u	no-unused-vars
10:44	warning	'res' is defined but never used	@typescript-eslint/no-unused-vars
10:49	warning	'next' is defined but never used. Allowed unused args must match /^_/u	no-unused-vars
10:49	warning	'next' is defined but never used	@typescript-eslint/no-unused-vars
25:39	warning	'next' is defined but never used. Allowed unused args must match /^_/u	no-unused-vars
25:39	warning	'next' is defined but never used	@typescript-eslint/no-unused-vars
19:20	warning	'_weight' is assigned a value but never used	@typescript-eslint/no-unused-vars
20:12	warning	'_language' is assigned a value but never used	@typescript-eslint/no-unused-vars
52:16	warning	'mailoptions' is defined but never used. Allowed unused args must match /^_/u	no-unused-vars
52:16	warning	'mailoptions' is defined but never used	@typescript-eslint/no-unused-vars
52:29	warning	'callback' is defined but never used. Allowed unused args must match /^_/u	no-unused-vars
52:29	warning	'callback' is defined but never used	@typescript-eslint/no-unused-vars
197:25	warning	'_error' is defined but never used	@typescript-eslint/no-unused-vars
39:44	warning	'isUserBrowserFirefox' is assigned a value but never used. Allowed unused vars must match /^_/u	no-unused-vars
39:44	warning	'isUserBrowserFirefox' is assigned a value but never used	@typescript-eslint/no-unused-vars
39:100	warning	'isUserLocaleEn' is assigned a value but never used. Allowed unused vars must match /^_/u	no-unused-vars
39:100	warning	'isUserLocaleEn' is assigned a value but never used	@typescript-eslint/no-unused-vars
9:22	warning	'_data' is defined but never used	@typescript-eslint/no-unused-vars
33:96	warning	'isUserLocalEn' is assigned a value but never used. Allowed unused vars must match /^_/u	no-unused-vars
33:96	warning	'isUserLocalEn' is assigned a value but never used	@typescript-eslint/no-unused-vars
5:26	warning	'data' is defined but never used. Allowed unused args must match /^_/u	no-unused-vars
5:26	warning	'data' is defined but never used	@typescript-eslint/no-unused-vars
5:28	warning	'data' is defined but never used. Allowed unused args must match /^_/u	no-unused-vars
5:28	warning	'data' is defined but never used	@typescript-eslint/no-unused-vars
7:25	warning	'data' is defined but never used. Allowed unused args must match /^_/u	no-unused-vars
7:25	warning	'data' is defined but never used	@typescript-eslint/no-unused-vars

Also seems fishy that we have both ESLint no-unused-vars and TypeScript-y @typescript-eslint/no-unused-vars rules enabled. Per the typescript-eslint docs:

"This rule extends the base eslint/no-unused-vars rule. It adds support for TypeScript features, such as types."

[Vinnl]

Also seems fishy that we have both ESLint no-unused-vars and TypeScript-y @typescript-eslint/no-unused-vars rules enabled.

Oops, that's my fault. We should probably disable the former, and apply the configuration we currently have for that rule to the TS version. Unless the TS version doesn't lint JS files, which I'm not sure about.

[pdehaan]

Actually, I built a quick little ESLint error/warning summarizer and ran it against the nextjs branch.
Looks like we should probably disable the jsdoc/* rule set which would remove about 79% of the warnings.
Disabling @typescript-eslint/no-explicit-any and @typescript-eslint/no-unused-vars would solve another 19% of the warnings.

import cp from "node:child_process";
import { inspect } from "node:util";

const ERROR_REGEXP = /^\s+\d+:\d+\s+(warning|error)\s+.*\s(.*?)$/i;

const errorMap = {};
let summary;

try {
  cp.execSync("npm run lint:js");
} catch (err) {
  const stderr = err.stdout.toString().split("\n");
  for (const line of stderr) {
    if (ERROR_REGEXP.test(line)) {
      const [, type, rule] = line.match(ERROR_REGEXP);
      errorMap[type] = errorMap[type] || {};
      errorMap[type][rule] = (errorMap[type][rule] || 0) + 1;
    }
    if (line.startsWith("✖")) {
      summary = line;
    }
  }
}

console.log(inspect({ ...errorMap, _summary: summary }, { sorted: true }));

OUTPUT

  {
    _summary: '✖ 142 problems (5 errors, 137 warnings)',
    error: {
      '@next/next/no-assign-module-variable': 2,
      'n/no-callback-literal': 1,
      'no-empty': 2
    },
    warning: {
      '@next/next/no-img-element': 1,
      '@typescript-eslint/no-explicit-any': 6,
      '@typescript-eslint/no-unused-vars': 20,
      'header/header': 2,
      'jsdoc/check-param-names': 1,
      'jsdoc/no-undefined-types': 13,
      'jsdoc/require-param-type': 6,
      'jsdoc/require-property-description': 40,
      'jsdoc/require-returns': 6,
      'jsdoc/require-returns-description': 14,
      'jsdoc/require-returns-type': 19,
      'jsdoc/valid-types': 9
    }
  }

• 78.8% of warnings are jsdoc/* warnings.
• 19.0% of warnings are typescript any/unused warnings.