The export keyword in JavaScript is used to make functions, variables, or objects available for use in other modules. It plays a pivotal role in modular code organization and encapsulation, allowing you to define what parts of a module can be accessed from outside that module. Here are the primary purposes of the export keyword:

Sharing Functionality: The export keyword enables you to share functions, variables, classes, or objects from one module with other modules. This promotes code reuse and modularity in your applications.

Module Encapsulation: By using export, you can define which parts of a module are considered the module's public API and are meant to be used by other modules. This encapsulation ensures that the internal implementation details of a module remain hidden from external code.

Named Exports: You can use the export keyword to create named exports, which allow you to specify the names of the elements that you want to expose from a module. This makes it clear and explicit which parts of the module are accessible.

Example:

// Exporting named variables and functions
export const variable1 = 'value1';
export function func1() { /* ... */ }

Default Exports: The export keyword is also used to create a default export from a module. A default export is a single entity that represents the primary functionality of the module. It's often used for exporting the main feature or class from a module.

Example:

// Exporting a default function
export default function() { /* ... */ }

Export All: You can use the export * from 'module' syntax to export all the named exports from another module. This allows you to re-export everything from one module in another module.

Example:

export * from './anotherModule';

Combining Exports: Modules can have both named exports and a default export. This allows you to export a set of related functionality using named exports and a primary piece of functionality using a default export.

Example:

// Named exports
export const variable1 = 'value1';
export function func1() { /* ... */ }
// Default export
export default function() { /* ... */ }

The export keyword is essential for creating modular and maintainable JavaScript code. It defines what is exposed to the outside world and what remains private within a module. This promotes better code organization, code sharing, and the separation of concerns in your applications.