previewable-iterator

Previewable Iterable/Iterator for JavaScript/TypeScript

Install

npm install previewable-iterator

API

import {
  PreviewableIterable,
  previewable,
} from "previewable-iterator";

class PreviewableIterable

PreviewableIterable implements IterableIterator, which means it provides proper interface for both Iterable and Iterator. About the interface, please refer to the following MDN documentation.

• Iteration protocols

constructor(iterator: Iterator)

It accepts an iterator and wraps it as PreviewableIterable.

However, rather than directly using new PreviewableIterable(...), you may prefer using the previewable(...) helper function.

PreviewableIterable#preview()

It additionally provides a preview to literally preview the result of the iterable. In other words, it returns a previewed { value, done } without actually consuming an iteration step.

previewable(iterable: Iterable)

It is a helper function for PreviewableIterable, accepts an iterable. It creates an iterator from the iterable, and apply it to PreviewableIterable.

// e.g.
const iter = previewable([1, 2, 3, 4]);

iter.next(); // { value: 1, done: false }
iter.next(); // { value: 2, done: false }
iter.preview(); // { value: 3, done: false }
iter.preview(); // { value: 3, done: false }
iter.next(); // { value: 3, done: false }

Development

# formatting scripts (using Prettier)
npm run check-format
npm run format

# build TypeScript
npm run build

# test
npm run test

The formatting scripts are automatically executed before commit or push.

License

MIT