Bundler API

Rolldown provides three main API functions for bundling your code programmatically.

`rolldown()`

rolldown() is the API compatible with Rollup's rollup function.

import { rolldown } from 'rolldown';

let bundle,
  failed = false;
try {
  bundle = await rolldown({
    input: 'src/main.js',
  });
  await bundle.write({
    format: 'esm',
  });
} catch (e) {
  console.error(e);
  failed = true;
}
if (bundle) {
  await bundle.close();
}
process.exitCode = failed ? 1 : 0;

See its reference for more details.

`watch()`

watch() is the API compatible with Rollup's watch function.

import { watch } from 'rolldown';

const watcher = watch({
  /* ... */
});
watcher.on('event', (event) => {
  if (event.code === 'BUNDLE_END') {
    console.log(event.duration);
    event.result.close();
  }
});

// Stop watching
watcher.close();

See its reference for more details.

`build()`

::: warning Experimental

This API is experimental and may change in patch releases.

:::

build() is the simplest option for most use cases. The API is similar to esbuild's build function. It bundles and writes in a single call with automatic cleanup.

import { build } from 'rolldown';

const result = await build({
  input: 'src/main.js',
  output: {
    file: 'bundle.js',
  },
});
console.log(result);

See its reference for more details.