This example demonstrates three JavaScript design patterns through code snippets: the Adapter, Iterator, and Singleton patterns. The Adapter pattern wraps a `ModifiedShipping` object to expose a `request` method compatible with the original `Shipping` interface. The Iterator pattern implements a custom `Iterator` class with `first`, `next`, `hasNext`, and `each` methods to sequentially traverse an array. The Singleton pattern uses a closure to ensure `getInstance` always returns the same object instance. The code uses plain JavaScript with no external libraries, and each pattern includes commented explanations of its purpose and trade-offs.