transducer-api-core-js-2.js

const isEven = value => value % 2 === 0;

const isFilteredAuthor = ({ name }, { author }) => {
  // if filter is not available, value is not filtered
  if (author === undefined) {
    return true;
  }
  // checks if names equal
  return name === author;
};
const isFilteredDate = ({ timestamp }, { from, to }) => {
  // if filter is not available, value is not filtered
  if (from === undefined || to === undefined) {
    return true;
  }
  // checks if date is within interval
  return from <= timestamp && timestamp <= to;
};

const coreJs = (posts, filters) => {
  let filteredPosts = [];
  // iterates over posts until filtered posts have any value
  for (let i = 0; i < posts.length && filteredPosts.length < 1; i++) {
    const post = posts[i];
    // applies filters
    if (isFilteredAuthor(post, filters) && isFilteredDate(post, filters)) {
      filteredPosts.push(post);
    }
  }
  return filteredPosts;
};

const posts = [
  {
    name: "Lorna Stiedemann",
    title: "Fugiat qui maiores illo.",
    timestamp: 1534534191881
  },
  {
    name: "Joel Will",
    title: "Ea consequatur eveniet ut qui et quae voluptatem.",
    timestamp: 1531221363376
  },
  {
    name: "Quincy Vandervort",
    title: "Rerum odit nemo in.",
    timestamp: 1535462116340
  }
];

coreJs(posts, { author: "Joel Will" })                              // [{ name: 'Joel Will', title: 'Ea consequatur eveniet ut qui et quae voluptatem.', timestamp: 1531221363376 }]
coreJs(posts, { author: "Joel Will", from: 0, to: 1531221363370 })  // []
coreJs(posts, { from: 0, to: 1535462116340 })                       // [{ name: 'Lorna Stiedemann', title: 'Fugiat qui maiores illo.', timestamp: 1534534191881 }]