Handle prettier with eslint (#314)

Props @adekbadek

scripts/check-diff.sh

@@ -308,7 +308,10 @@ function set_environment_variables {
 		done
 
 		# Make sure linter configs get copied linting directory since upsearch is relative.
-		for linter_file in .jshintrc .jshintignore .jscsrc .jscs.json .eslintignore .eslintrc .eslintrc.js .eslintrc.json .phpcs.xml phpcs.xml .phpcs.xml.dist phpcs.xml.dist phpcs.ruleset.xml ruleset.xml; do
+		#
+		# Eslint might depend on Prettier (https://github.com/prettier/eslint-plugin-prettier), so prettier config has to be copied into the linting directory.
+		# Both Eslint and Prettier might be configured as keys in package.json, so this file needs to also be imported.
+		for linter_file in .jshint* .jscs* .eslint* package.json .prettier* .phpcs* phpcs* ruleset.xml; do
 			if git ls-files "$linter_file" --error-unmatch > /dev/null 2>&1; then
 				if [ -L $linter_file ]; then
 					ln -fs $(git show :"$linter_file") "$LINTING_DIRECTORY/$linter_file"