Use Intl.ListFormat#format (#2122)

Author: fisker

rules/import-style.js

@@ -103,20 +103,6 @@ const getActualAssignmentTargetImportStyles = assignmentTarget => {
 	return [];
 };
 
-const joinOr = words => words
-	.map((word, index) => {
-		if (index === words.length - 1) {
-			return word;
-		}
-
-		if (index === words.length - 2) {
-			return word + ' or';
-		}
-
-		return word + ',';
-	})
-	.join(' ');
-
 const isAssignedDynamicImport = node =>
 	node.parent.type === 'AwaitExpression'
 	&& node.parent.argument === node
@@ -183,7 +169,7 @@ const create = context => {
 		}
 
 		const data = {
-			allowedStyles: joinOr([...allowedImportStyles.keys()]),
+			allowedStyles: new Intl.ListFormat('en-US', {type: 'disjunction'}).format([...allowedImportStyles.keys()]),
 			moduleName,
 		};
 

test/import-style.mjs

@@ -592,7 +592,7 @@ test({
 			errors: [{
 				messageId: 'importStyle',
 				data: {
-					allowedStyles: 'named, namespace or default',
+					allowedStyles: 'named, namespace, or default',
 					moduleName: 'no-unassigned',
 				},
 			}],