JavaScript API

const inputOptions = {
	// core input options
	external,
	input, // conditionally required
	plugins,

	// advanced input options
	cache,
	logLevel,
	makeAbsoluteExternalsRelative,
	maxParallelFileOps,
	onLog,
	onwarn,
	preserveEntrySignatures,
	strictDeprecations,

	// danger zone
	acorn,
	acornInjectPlugins,
	context,
	moduleContext,
	preserveSymlinks,
	shimMissingExports,
	treeshake,

	// experimental
	experimentalCacheExpiry,
	experimentalLogSideEffects,
	perf
};

const outputOptions = {
	// core output options
	dir,
	file,
	format,
	globals,
	name,
	plugins,

	// advanced output options
	assetFileNames,
	banner,
	chunkFileNames,
	compact,
	dynamicImportInCjs,
	entryFileNames,
	extend,
	externalImportAssertions,
	footer,
	generatedCode,
	hoistTransitiveImports,
	inlineDynamicImports,
	interop,
	intro,
	manualChunks,
	minifyInternalExports,
	outro,
	paths,
	preserveModules,
	preserveModulesRoot,
	sourcemap,
	sourcemapBaseUrl,
	sourcemapExcludeSources,
	sourcemapFile,
	sourcemapIgnoreList,
	sourcemapPathTransform,
	validate,

	// danger zone
	amd,
	esModule,
	exports,
	externalLiveBindings,
	freeze,
	indent,
	noConflict,
	sanitizeFileName,
	strict,
	systemNullSetters,

	// experimental
	experimentalMinChunkSize
};

const rollup = require('rollup');

const watchOptions = {...};
const watcher = rollup.watch(watchOptions);

watcher.on('event', event => {
  // event.code can be one of:
  //   START        — the watcher is (re)starting
  //   BUNDLE_START — building an individual bundle
  //                  * event.input will be the input options object if present
  //                  * event.output contains an array of the "file" or
  //                    "dir" option values of the generated outputs
  //   BUNDLE_END   — finished building a bundle
  //                  * event.input will be the input options object if present
  //                  * event.output contains an array of the "file" or
  //                    "dir" option values of the generated outputs
  //                  * event.duration is the build duration in milliseconds
  //                  * event.result contains the bundle object that can be
  //                    used to generate additional outputs by calling
  //                    bundle.generate or bundle.write. This is especially
  //                    important when the watch.skipWrite option is used.
  //                  You should call "event.result.close()" once you are done
  //                  generating outputs, or if you do not generate outputs.
  //                  This will allow plugins to clean up resources via the
  //                  "closeBundle" hook.
  //   END          — finished building all bundles
  //   ERROR        — encountered an error while bundling
  //                  * event.error contains the error that was thrown
  //                  * event.result is null for build errors and contains the
  //                    bundle object for output generation errors. As with
  //                    "BUNDLE_END", you should call "event.result.close()" if
  //                    present once you are done.
  // If you return a Promise from your event handler, Rollup will wait until the
  // Promise is resolved before continuing.
});

// This will make sure that bundles are properly closed after each run
watcher.on('event', ({ result }) => {
  if (result) {
  	result.close();
  }
});

// Additionally, you can hook into the following. Again, return a Promise to
// make Rollup wait at that stage:
watcher.on('change', (id, { event }) => { /* a file was modified */ })
watcher.on('restart', () => { /* a new run was triggered */ })
watcher.on('close', () => { /* the watcher was closed, see below */ })

// to stop watching
watcher.close();

const watchOptions = {
	...inputOptions,
	output: [outputOptions],
	watch: {
		buildDelay,
		chokidar,
		clearScreen,
		skipWrite,
		exclude,
		include
	}
};

const { loadConfigFile } = require('rollup/loadConfigFile');
const path = require('node:path');
const rollup = require('rollup');

// load the config file next to the current script;
// the provided config object has the same effect as passing "--format es"
// on the command line and will override the format of all outputs
loadConfigFile(path.resolve(__dirname, 'rollup.config.js'), {
	format: 'es'
}).then(async ({ options, warnings }) => {
	// "warnings" wraps the default `onwarn` handler passed by the CLI.
	// This prints all warnings up to this point:
	console.log(`We currently have ${warnings.count} warnings`);

	// This prints all deferred warnings
	warnings.flush();

	// options is an array of "inputOptions" objects with an additional
	// "output" property that contains an array of "outputOptions".
	// The following will generate all outputs for all inputs, and write
	// them to disk the same way the CLI does it:
	for (const optionsObj of options) {
		const bundle = await rollup.rollup(optionsObj);
		await Promise.all(optionsObj.output.map(bundle.write));
	}

	// You can also pass this directly to "rollup.watch"
	rollup.watch(options);
});