Tools: Run pre-commit hook tasks in parallel

lint-staged.config.js

@@ -1,22 +1,27 @@
 module.exports = {
-	// Don't compile when committing as it will process all TS files in the
-	// monorepo, which is too slow. Errors should be checked during development
-	// using `npm run watch`.
+	// # About TypeScript compilation
+	//
+	// Don't compile when committing as it will process all TS files in the monorepo, which is too
+	// slow. Errors should be checked during development using `yarn watch`.
 	//
 	// Or if we add this back, we could do something like this:
 	// https://stackoverflow.com/a/44748041/561309
 	//
-	// The script would check where the TS file is located, then use the right
-	// tsconfig.json file along with the tsconfig override.
+	// The script would check where the TS file is located, then use the right tsconfig.json file
+	// along with the tsconfig override.
 	//
-	// '**/*.ts?(x)': () => 'npm run tsc',
-	'*.{js,jsx,ts,tsx}': [
-		'yarn checkIgnoredFiles',
-		'yarn spellcheck',
-		'yarn packageJsonLint',
-		'yarn linter-precommit',
-	],
-	'*.{md,mdx}': [
-		'yarn spellcheck',
-	],
+	// # Running tasks in parallel
+	//
+	// lint-staged does not allow running concurrent tasks for the same extension, because multiple
+	// tasks might modify the same files. This doesn't apply to us because only one task modifies
+	// files (the linter task) while others only notify about errors. So to go around this we add
+	// this fake extension "task?" to make lint-staged think those are different extension tasks
+	// that can run in parallel.
+	//
+	// See https://github.com/lint-staged/lint-staged/issues/934#issuecomment-743299357
+	'*.{js,jsx,ts,tsx,task1}': 'yarn checkIgnoredFiles',
+	'*.{js,jsx,ts,tsx,task2}': 'yarn spellcheck',
+	'*.{js,jsx,ts,tsx,task3}': 'yarn packageJsonLint',
+	'*.{js,jsx,ts,tsx,task4}': 'yarn linter-precommit',
+	'*.{md,mdx}': 'yarn spellcheck',
 };