Importing Modules

To import a module into your JavaScript file with Rollup.js, you can use the import keyword followed by the module path. The module path can be either an absolute path or a relative path to the current file. Here’s an example:

import { foo, bar } from './myModule.js';

In the example above, we are importing the foo and bar named exports from the myModule.js file. You can also import the default export using the default keyword:

import myFunction from './myModule.js';

Rollup.js will analyze your code and bundle the necessary modules into the final output file, eliminating any unused code by tree shaking.

Exporting Modules

To export a module in Rollup.js, you can use the export keyword followed by the entities you want to export. Here are a few examples:

export const myVariable = 'Hello, Rollup!';

In the example above, we are exporting a constant variable myVariable. You can also export functions, classes, and objects:

export function myFunction() {
  // Function implementation
}

export class MyClass {
  // Class definition
}

export default myDefaultFunction;

The export default keyword is used to set the default export for a module. You can only have one default export per module, and it can be imported without using curly braces:

import myDefaultFunction from './myModule.js';

Conclusion

Understanding the import and export syntax in Rollup.js is crucial for building modular and maintainable JavaScript applications. With Rollup.js, you can easily import and export modules, allowing you to structure your codebase and manage dependencies effectively. Make sure to leverage the power of tree shaking to eliminate any unused code from your final bundled output.

#rollupjs #javascript