svelte/rollup/rollup.config.main.js

import path from 'path';
import nodeResolve from 'rollup-plugin-node-resolve';
import commonjs from 'rollup-plugin-commonjs';
import json from 'rollup-plugin-json';
import typescript from 'rollup-plugin-typescript';

const src = path.resolve('src');

export default {
	entry: 'src/index.ts',
	moduleName: 'svelte',
	targets: [{ dest: 'compiler/svelte.js', format: 'umd' }],
	plugins: [
		{
			resolveId(importee, importer) {
				// bit of a hack — TypeScript only really works if it can resolve imports,
				// but they misguidedly chose to reject imports with file extensions. This
				// means we need to resolve them here
				if (
					importer &&
					importer.startsWith(src) &&
					importee[0] === '.' &&
					path.extname(importee) === ''
				) {
					return path.resolve(path.dirname(importer), `${importee}.ts`);
				}
			}
		},
		nodeResolve({ jsnext: true, module: true }),
		commonjs(),
		json(),
		typescript({
			include: 'src/**',
			exclude: 'src/shared/**',
			typescript: require('typescript')
		})
	],
	sourceMap: true
};