nextjs-demo

next.js demo using react 19 rc
git clone https://9o.is/git/nextjs-demo.git
objects.ts

(1812B)
      1 type KeysOfType<T, U> = {
      2     [K in keyof T]: T[K] extends U ? K : never
      3 }[keyof T]
      4 
      5 type NumberKeysOf<T> = KeysOfType<T, number>
      6 
      7 export const SORT_TYPES = ["ascending", "descending"] as const
      8 export type SortType = typeof SORT_TYPES[number]
      9 
     10 export function isSortType(value: string | undefined | null): value is SortType {
     11     return value === "ascending" || value === "descending"
     12 }
     13 
     14 export function isPromise<T>(value: unknown): value is Promise<T> {
     15     return value instanceof Promise
     16 }
     17 
     18 export function asArray<T>(value: T | T[] | undefined | null): T[] {
     19     return Array.isArray(value) ? value : 
     20         value !== undefined && value !== null ? [value] : []
     21 }
     22 
     23 export function filterByProp<T extends object>(prop: keyof T, value: T[keyof T], objects: T[]): T[] {
     24     return objects.filter(object => object[prop] === value)
     25 }
     26 
     27 export function sortByProp<T,>(prop: NumberKeysOf<T>, order: SortType, objects: T[]): T[] {
     28     return [...objects].sort((a: T, b: T) => {
     29         if (!order || typeof a[prop] !== "number" || typeof b[prop] !== "number") return 0
     30         if (order === "ascending") return a[prop] - b[prop]
     31         return b[prop] - a[prop]
     32     })
     33 }
     34 
     35 export function minByProp<T extends object>(prop: NumberKeysOf<T>, objects: T[]): T | null {
     36     if (objects.length === 0) return null
     37     if (objects.length === 1) return objects[0]
     38 
     39     const [fst, snd, ...tail] = objects
     40     const min = fst[prop] < snd[prop] ? fst : snd
     41     return minByProp(prop, [min, ...tail])
     42 }
     43 
     44 // Alternative implementation using reduce
     45 // const minByProp = <T extends object>(prop: NumberKeysOf<T>, objects: T[]): T | undefined => {
     46 //   if (objects.length === 0) return undefined
     47 
     48 //   return objects.reduce((minObj, currentObj) => {
     49 //     return currentObj[prop] < minObj[prop] ? currentObj : minObj
     50 //   })
     51 // }