feature: --package-json CLI argument

Support explicitly specified package.json in CLI.

src/cli.ts

@@ -6,14 +6,24 @@ import type swcType from '@swc/core'
 import { convert } from './index'
 
 const {
-	values: { filename, cwd, output, help, set: overrideValues },
+	values: {
+		filename,
+		'package-json': packageJson,
+		cwd,
+		output,
+		help,
+		set: overrideValues,
+	},
 } = parseArgs({
 	options: {
 		filename: {
 			type: 'string',
 			short: 'f',
 			default: 'tsconfig.json',
 		},
+		'package-json': {
+			type: 'string',
+		},
 		cwd: {
 			type: 'string',
 			short: 'c',
@@ -42,7 +52,8 @@ Usage: tsconfig-to-swcconfig [options]
 Alias: t2s [options]
 
 Options:
-  -f, --filename <filename>  filename to tsconfig (default: "tsconfig.json")
+  -f, --filename <filename>  path to tsconfig (default: "tsconfig.json")
+  --package-json <package.json> path to package.json (default: search cwd)
   -c, --cwd <cwd>            cwd (default: "${process.cwd()}")
   -o, --output <output>      output file (default: stdout)
   -s, --set <name>=<value>   set additional swcrc options
@@ -75,7 +86,7 @@ const overrides = overrideValues?.reduce((all, a) => {
 	return all
 }, {} as any) as swcType.Options
 
-const swcConfig = convert(filename, cwd, overrides)
+const swcConfig = convert(filename, cwd, overrides, packageJson)
 
 if (output) {
 	writeFile(output, JSON.stringify(swcConfig, null, 2), (err) => {

src/index.ts

@@ -12,15 +12,17 @@ export function convert(
 	cwd: string = process.cwd(),
 	/** swc configs to override */
 	swcOptions?: swcType.Options,
+	packageJsonPath?: string | undefined,
 ): swcType.Options {
 	const tsOptions = getTSOptions(filename, cwd) ?? {}
-	return convertTsConfig(tsOptions, swcOptions, cwd)
+	return convertTsConfig(tsOptions, swcOptions, cwd, packageJsonPath)
 }
 
 export function convertTsConfig(
 	tsOptions: TsConfigJson.CompilerOptions,
 	swcOptions: swcType.Options = {},
 	cwd: string = process.cwd(),
+	packageJsonPath?: string | undefined,
 ): swcType.Options {
 	// https://json.schemastore.org/tsconfig
 	const {
@@ -51,7 +53,7 @@ export function convertTsConfig(
 		{
 			sourceMaps: sourceMap,
 			module: {
-				type: moduleType(module, cwd),
+				type: moduleType(module, getPackageJson(packageJsonPath, cwd)),
 				strictMode: alwaysStrict || !noImplicitUseStrict,
 				noInterop: !esModuleInterop,
 			} satisfies swcType.ModuleConfig,
@@ -95,29 +97,20 @@ type Module = typeof availableModuleTypes[number]
 
 function moduleType(
 	m: TsConfigJson.CompilerOptions.Module | undefined,
-	cwd: string = process.cwd(),
+	packageJson: { type?: string },
 ): Module {
 	const module = (m as unknown as string)?.toLowerCase()
 	if (availableModuleTypes.includes(module as any)) {
 		return module as Module
 	}
 
-	const es6Modules = [
-		'es2015',
-		'es2020',
-		'es2022',
-		'esnext',
-		'none',
-	] as const
+	const es6Modules = ['es2015', 'es2020', 'es2022', 'esnext', 'none'] as const
 	if (es6Modules.includes(module as any)) {
 		return 'es6'
 	}
 
-	const nodeModules = [
-		'node16',
-		'nodenext',
-	] as const
-	if (nodeModules.includes(module as any) && getPackageJson(cwd)?.type === 'module') {
+	const nodeModules = ['node16', 'nodenext'] as const
+	if (nodeModules.includes(module as any) && packageJson.type === 'module') {
 		return 'es6'
 	}
 

src/utils.ts

@@ -16,14 +16,16 @@ export function getTSOptions(
 	return config.compilerOptions ?? null
 }
 
-export function getPackageJson(cwd: string = process.cwd()) {
-	const result = findUpSync('package.json', { cwd })
+export function getPackageJson(
+	packageJsonPath: string | undefined,
+	cwd: string,
+): { type?: string } {
+	const result = findUpSync(packageJsonPath || 'package.json', { cwd })
 	if (!result) {
-		return null
+		return {}
 	}
 
-	const packageJson = JSON.parse(fs.readFileSync(result, 'utf-8'))
-	return packageJson
+	return JSON.parse(fs.readFileSync(result, 'utf-8'))
 }
 
 // the following code is copied from https://github.com/sindresorhus/find-up-simple/blob/ec263e63e3198ce3cdadd49decb9940ac9997bf3/index.js#L32C1-L53C2

test/cli.test.mjs

@@ -137,4 +137,26 @@ describe('cli', { concurrency: true }, () => {
 		match(stdout, /"not1": "1x"/)
 		match(stdout, /"not2": "x2"/)
 	})
+
+	it('should convert tsconfig.json with package.json path', async () => {
+		const { stdout, stderr } = await pExe('node', [
+			'dist/cli.js',
+			'--filename',
+			resolve(
+				__dirname,
+				'fixtures',
+				'tsconfig-with-package-json',
+				'tsconfig.json',
+			),
+			'--package-json',
+			resolve(
+				__dirname,
+				'fixtures',
+				'tsconfig-with-package-json',
+				'package.json',
+			),
+		])
+		strictEqual(stderr, '')
+		match(stdout, /"type": "es6"/)
+	})
 })