Function getMain

src/index.js:277–321

({ options, entry, format })

}

function getMain({ options, entry, format }) {
	const { pkg } = options;
	const pkgMain = options['pkg-main'];
	const pkgTypeModule = pkg.type === 'module';

	if (!pkgMain) {
		return options.output;
	}

	let mainNoExtension = options.output;
	if (options.multipleEntries) {
		let name = entry.match(new RegExp(/([\\/])index/.source + EXTENSION.source))
			? mainNoExtension
			: entry;
		mainNoExtension = resolve(dirname(mainNoExtension), basename(name));
	}
	mainNoExtension = mainNoExtension.replace(EXTENSION, '');

	const mainsByFormat = {};

	mainsByFormat.es = replaceName(
		pkg.module && !pkg.module.match(/src\//)
			? pkg.module
			: pkg['jsnext:main'] || (pkgTypeModule ? 'x.esm.js' : 'x.esm.mjs'),
		mainNoExtension,
	);

	mainsByFormat.modern = replaceName(
		(pkg.exports && walk(pkg.exports, pkgTypeModule)) ||
			(pkg.syntax && pkg.syntax.esmodules) ||
			pkg.esmodule ||
			(pkgTypeModule ? 'x.modern.js' : 'x.modern.mjs'),
		mainNoExtension,
	);
	mainsByFormat.cjs = replaceName(
		pkg['cjs:main'] || (pkgTypeModule ? 'x.cjs' : 'x.js'),
		mainNoExtension,
	);
	mainsByFormat.umd = replaceName(
		pkg['umd:main'] || pkg.unpkg || 'x.umd.js',
		mainNoExtension,
	);

	return mainsByFormat[format] || mainsByFormat.cjs;
}

// shebang cache map because the transform only gets run once
const shebang = {};