From 8825cdbabea4616a61f06cddc78e1d114523d8d5 Mon Sep 17 00:00:00 2001
From: Guy Bedford <guybedford@gmail.com>
Date: Tue, 2 Apr 2019 06:28:40 +0200
Subject: [PATCH] Support Node-style format aliases (#2783)

* support Node-style format aliases

* remove unnecessary fallback

* add formats to typings
---
 src/rollup/types.d.ts     | 11 ++++++++++-
 src/utils/mergeOptions.ts | 12 +++++++++++-
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/rollup/types.d.ts b/src/rollup/types.d.ts
index 9fec100e5fc..189c49e8265 100644
--- a/src/rollup/types.d.ts
+++ b/src/rollup/types.d.ts
@@ -287,7 +287,16 @@ export interface InputOptions {
 	watch?: WatcherOptions;
 }
 
-export type ModuleFormat = 'amd' | 'cjs' | 'system' | 'es' | 'esm' | 'iife' | 'umd';
+export type ModuleFormat =
+	| 'amd'
+	| 'cjs'
+	| 'commonjs'
+	| 'es'
+	| 'esm'
+	| 'iife'
+	| 'module'
+	| 'system'
+	| 'umd';
 
 export type OptionsPaths = Record<string, string> | ((id: string) => string);
 
diff --git a/src/utils/mergeOptions.ts b/src/utils/mergeOptions.ts
index 8f8c2629a98..00455edc6e9 100644
--- a/src/utils/mergeOptions.ts
+++ b/src/utils/mergeOptions.ts
@@ -229,7 +229,17 @@ function getOutputOptions(
 	command: GenericConfigObject = {}
 ): OutputOptions {
 	const getOption = createGetOption(config, command);
-	const format = getOption('format');
+	let format = getOption('format');
+
+	// Handle format aliases
+	switch (format) {
+		case 'esm':
+		case 'module':
+			format = 'es';
+			break;
+		case 'commonjs':
+			format = 'cjs';
+	}
 
 	return {
 		amd: { ...config.amd, ...command.amd },