exports

• Type: optional exports: "auto" | "named" | "default" | "none"

Defined in: options/output-options.ts:122

Which exports mode to use.

When 'auto' is used, Rolldown will automatically determine the export mode based on the exports of the input modules. If the input modules have a single default export, then 'default' mode is used. If the input modules have named exports, then 'named' mode is used. If there are no exports, then 'none' mode is used.

'default' can only be used when the input modules have a single default export. 'none' can only be used when the input modules have no exports. Otherwise, Rolldown will throw an error.

The difference between 'default' and 'named' affects how other people can consume your bundle. If you use 'default', a CommonJS user could do this, for example:

// your-lib package entry
export default 'Hello world';

// a CommonJS consumer
/* require( "your-lib" ) returns "Hello world" */
const hello = require('your-lib');

With 'named', a user would do this instead:

// your-lib package entry
export const hello = 'Hello world';

// a CommonJS consumer
/* require( "your-lib" ) returns {hello: "Hello world"} */
const hello = require('your-lib').hello;
/* or using destructuring */
const { hello } = require('your-lib');

The wrinkle is that if you use 'named' exports but also have a default export, a user would have to do something like this to use the default export:

// your-lib package entry
export default 'foo';
export const bar = 'bar';

// a CommonJS consumer
/* require( "your-lib" ) returns {default: "foo", bar: "bar"} */
const foo = require('your-lib').default;
const bar = require('your-lib').bar;
/* or using destructuring */
const { default: foo, bar } = require('your-lib');

TIP

There are many tools that are capable of resolving a CommonJS require(...) call with an ES module. If you are generating CommonJS output that is meant to be interchangeable with ESM output for those tools, you should always use 'named' export mode. The reason is that most of those tools will by default return the namespace of an ES module on require where the default export is the .default property.

In other words for those tools, you cannot create a package interface where const lib = require("your-lib") yields the same as import lib from "your-lib". With 'named' export mode however, const {lib} = require("your-lib") will be equivalent to import {lib} from "your-lib".

Default

'auto'