Is Rollup 4 not a constructor?

The question "Is Rollup 4 not a constructor?" stems from a common misunderstanding about how Rollup, particularly version 4, is used. Rollup is a module bundler, not a class or a constructor that you directly instantiate using the `new` keyword like in traditional JavaScript object creation. Instead, you utilize Rollup through its command-line interface (CLI) or via a configuration file (typically `rollup.config.js`).

Rollup is designed to take your source JavaScript or TypeScript code and bundle it into one or more files suitable for distribution. The core library doesn't expose a class intended to be constructed. Rollup operates by processing module dependencies and producing an optimized build output, not by directly creating instances of its core engine. Therefore, you wouldn't attempt to use `new Rollup()`, because it's not intended to be used that way.

When configuring Rollup in your project, you are essentially defining options like input files, output formats, and plugins. The configuration instructs Rollup on how to perform the bundling process. For instance, you'd use the Rollup CLI tool or programmatically interact with its API to trigger the bundling logic. Therefore, if you are encountering an error suggesting "Rollup is not a constructor" it indicates that you are attempting to use Rollup in a way it is not designed to be used.

In summary, Rollup 4 (or any other version of Rollup) is not meant to be used as a constructor; it's a tool. You manage the bundling process through its command line or by configuring the tool in your Javascript environment. Understanding this distinction is essential to effectively leverage Rollup for your projects.