リアクティブ人間になるためにいまイベントハンドラの設定こうやってる.js

import KeyStringDetector from 'key-string'

const detector = new KeyStringDetector();

function changeModeIntent(DOM) {
  const documentStream = DOM.select('.header-format-switcher-document-button').events('click').map(() => 'document');
  const slideStream = DOM.select('.header-format-switcher-slide-button').events('click').map(() => 'slide');
  const changeModeStream = documentStream.merge(slideStream);
  return { changeModeStream };
}

function keyboardStreamIntent(DOM) {
  const keyboardStream = DOM.select(':root').events('keydown').map((event) => detector.detect(event));
  return { keyboardStream };
}

function moveToFirstSlideIntent(DOM) {
  const firstSlideStream = DOM.select('.header-slide-controller-first-slide-button').events('click');
  return { firstSlideStream };
}

function moveToLastSlideIntent(DOM) {
  const lastSlideStream = DOM.select('.header-slide-controller-last-slide-button').events('click');
  return { lastSlideStream };
}

function moveToNextSlideIntent(DOM) {
  const keyboardStream = keyboardStreamIntent(DOM).keyboardStream;
  const fromKeyboard = keyboardStream.filter((keyString) => keyString === 'Right');
  const fromClick = DOM.select('.header-slide-controller-next-slide-button').events('click');
  const nextSlideStream = fromKeyboard.merge(fromClick);
  return { nextSlideStream };
}

function moveToPreviousSlideIntent(DOM) {
  const keyboardStream = keyboardStreamIntent(DOM).keyboardStream;
  const fromKeyboard = keyboardStream.filter((keyString) => keyString === 'Left');
  const fromClick = DOM.select('.header-slide-controller-previous-slide-button').events('click');
  const previousSlideStream = fromKeyboard.merge(fromClick);
  return { previousSlideStream };
}

export default function (DOM) {
  return {
    ...changeModeIntent(DOM),
    ...moveToFirstSlideIntent(DOM),
    ...moveToLastSlideIntent(DOM),
    ...moveToNextSlideIntent(DOM),
    ...moveToPreviousSlideIntent(DOM)
  };
}

DOMから提供されるイベントソースを入力として受け取り、ユーザが何を求めているのかを表すイベントソースを出力として返す関数を、intent として公開している。

intentは、更に小さな複数のintentに分割できるように実装してる。