Package name

postkit-filter-sort

Purpose

A utility library for filtering and sorting posts by status, tag, date, and title.

Exports

filterByStatus

• Input: posts: Post[], status: PostStatus
• Output: Post[]
• Description: Returns a new list of Posts that's filtered by Status

filterByTag

• Input: posts: Post[], tag:string
• Output: Post[]
• Description: Returns a new list of Posts that's filtered by Tag

sortByDate

• Input: posts: Post[], direction?: 'asc' | 'desc'
• Output: Post[]
• Description: Returns a new list of Posts sorted by date. Defaults to 'desc' (newest first) if no direction is provided.

sortByTitle

• Input: posts: Post[], direction?: 'asc' | 'desc'
• Output: Post[]
• Description: Returns a new list of Posts sorted by Title. Defaults to 'asc' (A → Z) if no direction is provided.

Example Usage

import { filterByStatus, filterByTag, sortByDate, sortByTitle } from 'postkit-filter-sort'

// a simple list of posts
const posts = [post1, post2, post3]

// filter by status
const drafts = filterByStatus(posts, 'draft')

// filter by tag
const tagged = filterByTag(posts, 'typescript')

// sort by title (A → Z by default)
const byTitle = sortByTitle(posts)

// sort by title Z → A
const byTitleDesc = sortByTitle(posts, 'desc')

// sort by date (newest first by default)
const byDate = sortByDate(posts)

// sort by date oldest first
const byDateAsc = sortByDate(posts, 'asc')

Edge Cases

• Empty array: If posts is empty, all functions return []

• Case sensitivity (filterByTag): Tags are normalized to lowercase before matching. 'Popular' will match posts tagged 'popular'

• Tie breaking (sortByDate, sortByTitle): If two posts share the same date or title, they are sorted by id as a tiebreaker

• Combining filter and sort: Functions can be chained — the caller controls the order:

const result = sortByDate(filterByStatus(posts, "draft"));

Design Notes

• Decided to return a new array instead of mutating the current array for filter and sort for performance issue. If the user wants to access the original array, then there's multiple API calls that needs to happen instead of just referring to the original array
• Chose asc | desc as direction instead of boolean. It would be difficult for users to ascertain whether true is for ascending or descending order. Avoiding "magic booleans"
• Direction is optional with a default because requiring it every time would be inconvenient. Most users of a publishing app want to see the newest posts first, so sortByDate defaults to 'desc' and sortByTitle defaults to 'asc' (A → Z) for natural alphabetical reading.