export

In JavaScript, the export keyword makes a module’s functions, classes, and values available to other modules, which load them with import. Export declarations work only at the top level of a module.

A module can have any number of named exports. It can put export in front of a declaration, or list existing bindings in braces and rename them with as. It can also have one default export, marked with default, which importers receive under a name of their choice. Exports are live bindings, so when the exporting module reassigns a variable, importers see the new value.

Re-exports combine export with from to pass along another module’s exports without creating local bindings. The export * from form re-exports every named export but skips the default export, while export * as <name> from gathers all of the module’s exports, the default included, into one namespace object. Modules and export were added in ES2015, and the export * as <name> from form in ES2020.

export <declaration>;
export { <name> [as <exportedName>], ... };
export default <expression>;

export { <name> [as <exportedName>], ... } from "<specifier>";
export * from "<specifier>";
export * as <namespace> from "<specifier>";

export let count = 0;

export function increment() {
  count += 1;
}

export default function reset() {
  count = 0;
}

export { count as clicks, increment as click } from "./counter.mjs";

import { clicks, click } from "./index.mjs";

console.log(`Before: ${clicks}`);
click();
click();
console.log(`After: ${clicks}`);

$ node main.mjs
Before: 0
After: 2