A shortcut utility JS library for rapidly interacting with objects, dates, and functions.

// Normal use
import { map } from "cut"
map({ a: 1 }, (v) => v + 1) //= {"a":2}

// Proxy use, access .data or .error
import cut from "cut"
cut({ a: 1 }).map((v) => v + 1).data //= {"a":2}
cut({ a: 1 }).x.y.error //= new Error()

// Prototype use, call directly on the object
import "cut?window+prototype"
({ a: 1 }).map((v) => v + 1) //= {"a":2}

// Format a Date
new Date("2000").format("YYYY-QQ") //= "2000-Q1"
new Date("2000").format("day, month, year", "en") //= "January 1, 2000"
new Date("2000T00:00").format("long, short", "ja") //= "2000年1月1日 0:00"

// Format a String
"hello_world".format() //= "Hello World"
"hello_world".format("camel") //= "helloWorld"
"{}_{}".format(["hello", "world"]) //= "hello_world"

// Format a Number
0.30000000000000004.format() //= "0.3"
0.111.format("+0.##%") //= "+11.1%"
123456.789.format(2) //= "120k"
123456.789.format(".") //= "123,457"
123456.789.format("CN¥") //= "CN¥123,456.79"

// Parse a Date
new Date("2000T00:00").parse("tomorrow") //= new Date("2000-01-02T00:00:00+01:00")
new Date("2000T00:00").parse("yesterday at 3pm") //= new Date("1999-12-31T15:00:00+01:00")
new Date("2000T00:00").parse("in one hour, two minutes and thirty-four seconds") //= new Date("2000-01-01T01:02:34+01:00")
new Date("2000T00:00").parse("6:30pm in three days") //= new Date("2000-01-04T18:30:00+01:00")

// Manipulate a Date
new Date("2000").plus("1 month").end("month").format("YYYY-MM-DD hh:mm") //= "2000-02-29 23:59"
new Date("2000").minus({ years: 1, months: 2 }).plus("1 year, 2 months").toISOString().slice(0, 10) //= "2000-01-01"

// Manipulate an Object or Array
const users = [
  { name: "John", age: 30, city: "London" },
  { name: "Jane", age: 14, city: "New York" },
  { name: "Jean", age: 35, city: "Paris" },
]
const usersByCity = users.sort("-age").group("city") //~ {"Paris":[{"name":"Jean","age":35...}
const avgAgeByCity = usersByCity.map((g) => g.mean("age")) //~ {"Paris":35...}

// Add a Function
cut(Array, "transpose", (arr) => arr[0].map((_, i) => arr.map((row) => row[i])))

// Add a shortcut
cut("shortcut", "transpose", (fn, arr) => {
  if (arr.some((row) => row.length !== arr[0].length)) throw new Error("Not a matrix")
  return fn(arr)
})

// Add an alias
cut(Array, "swap", cut.Array.transpose)

// And use it
const matrix = [[1, 2, 3], [4, 5, 6]]
matrix.swap() //= [[1,4],[2,5],[3,6]]
const invalid = [[1], [2, 3]]
invalid.transpose() //! Error: Not a matrix

Functions

Generic	Object	Array	Function	String	Number	Date	RegExp
is	keys	map	decorate	lower	duration	relative	escape
equal	values	reduce	promisify	upper	format	getWeek	plus
access	entries	filter	partial	capitalize		getQuarter	minus
transform	fromEntries	find	memoize	words		getLastDate
	map	findIndex	every	format		getTimezone
	reduce	sort	wait			format
	filter	group	debounce			modify
	find	unique	throttle			parse
	findIndex	min				plus
		max				minus
		sum				start
		mean				end
		median

Development

bun i @js-temporal/polyfill lodash-es
bun test --watch --coverage

Roadmap

• Interactive Docs & Tests: https://raw.githack.com/vbrajon/rawjs/cut/index.html
• Replace cutest by bun test
• Iterator or AsyncIterator
• Additional Fn (forEach, findIndex, findLastIndex, some, every, flat, flatMap, reduceRight, concat, slice)
• Fuzzy tests
• Typescript / TSDoc
• Monaco Editor
• Collaboration / Multiplayer / CTRL-S to PR
• Blog Post / Hacker News / Product Hunt

---

• lodash or underscore or just or sugar
• date-fns or moment or dayjs or tempo
• ixjs or rxjs
• mathjs
• xstate
• motion
• microdiff