🏂 @e280/stz

my typescript everyday carry

environment-agnostic zero-dependency tools and utilities. by https://e280.org/

🍴 utensils
⏳ async/fns
📣 subby
🧹 housekeeping
🎲 rand
✅ ok, err, result
🧬 hex and more

npm install @e280/stz

import {got} from "@e280/stz"

🍴 utensils

• got — throw an error if the value is null or undefined.

  const value = got(nullableValue)

• need — return a Map value, or throw an error if missing.

  const value = need(map, "my_key")

• guarantee — get-or-create a Map value.

  const value = guarantee(map, "my_key", () => 123)

• setEntries — set many Map entries at once.

  setEntries(map, [["my_key1", 123], ["my_key2", 234]])

• count — iterate numbers.

  for (const i of count(4))
    console.log(i)

• grid — iterate columns and rows.

  for (const [x, y] of grid(2, 4))
    console.log(x, y)

• arraylimit — limit array length by dropping oldest.

  const trimmed = arraylimit(["a", "b", "c", "d"], 2)
    // ["c", "d"]
    // returns new array if trimming happens,
    // otherwise returns the same array unchanged.

• pipe — run data through several fns.

  const result = pipe(rawData)
    .to(parse)
    .to(validate)
    .to(normalize)
    .done()

• obmap — map over object entries.

  const alpha = {alpha: 1, bravo: 2, charlie: 3}

  obmap(alpha, n => n * 10)
    // {alpha: 10, bravo: 20, charlie: 30}

• obfilter — filter object entries.

  obfilter(alpha, n => n > 1)
    // {bravo: 2, charlie: 3}

• deepFreeze — recursively Object.freeze an object tree.

  const freezie = deepFreeze({alpha: 123})
  
  freezie.alpha = 5 // throws error

• deepEqual — check if two object trees have the same primitive values.

  deepEqual({alpha: 123}, {alpha: 123})
    // true

• isHappy — check the identity of things with proper type guards.

  isHappy(0) // true if not null nor undefined.
  isSad(undefined) // true if null or undefined.
  isBoolean(true) // true
  isNumber(123) // true
  isString("hello") // true
  isBigint(123n) // true
  isArray([]) // true
  isObject({}) // true
  isFn(() => {}) // true
  isSymbol(Symbol()) // true

• seconds — durations and timestamps.
  durations:

  seconds(1) // 1000
  minutes(1)
  hours(1)
  days(1)

  timestamps after Date.now:

  futureSeconds(1)
  futureMinutes(1)
  futureHours(1)
  futureDays(1)

  timestamps before Date.now:

  pastSeconds(1)
  pastMinutes(1)
  pastHours(1)
  pastDays(1)

⏳ async/fns

• nap — return a promise that resolves later.

  await nap(1000) // sleep for one second.

• cycle — repeatedly call the fn back-to-back.

  const stop = cycle(async() => {
    console.log("hello!", Date.now())
    await nap(1000) // once per second.
  })

  stop() // cancel the cycle.

• concurrent — await a group of named promises.

  const {user, settings} = await concurrent({
    user: myFetchUser(),
    settings: myFetchSettings(),
  })

• defer — a promise you can resolve/reject from outside.

  const ready = defer<string>()
  
  ready.resolve("hello")
  
  await ready
    // "hello"

  ready.reject(new Error("rejected"))

• collect — async iterable to array.

  const entries = await collect(kv.entries())

• once — only execute the fn one time.

  const init = once(() => connect())
  init()
  init() // doesn't initialize twice.

• queue — make async fn calls work one-at-a-time.

  const save = queue(async(myData: string) => myWriteData(myData))
  
  await Promise.all([save("a"), save("b"), save("c")])
    // actually executes sequentially.

• deadline — add an expiry timeout.

  const connection = await deadline(10_000, connect)
    // throw DeadlineError after 10s unless connect resolves.
    // connect can be a promise or an async fn.

• debounce — dedupe calls over time.

  const search = debounce(250, async(s: string) => query(s))
  
  search("l")
  search("lo")
  await search("lol") // last one actually runs.

• microbounce — dedupe calls in this microtask.

  let count = 0
  const run = microbounce(() => count++)
  
  const done = run()
  run()
  run()
  
  await done
  count // 1

📣 subby

• subby — create a subscriber fn.

  const on = subby<[number]>()

  const off = on(x => console.log(x))

  on.publish(123)
    // 123

  off() // stop listening.

• pubby — create a publisher fn.

  const publish = pubby<[number]>()

  const off = publish.on(x => console.log(x))

  publish(123)
    // 123

  off() // stop listening.

• 🧙‍♂️ 'subby' and 'pubby' give you the same goody-bag.

  // limited 'on' and 'publish' fns without whole toolkit.
  const {on, publish} = subby()

  const {publishAsync} = subby()
  
  await publishAsync(123)
    // awaits every listener (they can be async).

  const [value] = await on.next() // wait for the next publish.
    // value is 123

  on.set.size // direct access to the set of listeners.

🧹 housekeeping

• ev — event listeners.

  import {ev} from "@e280/stz"
  
  const off = ev(window, {
      keydown: event => console.log(event),
      keyup: event => console.log(event),
  })
  
  off() // removes both listeners

• disposer — cleanup resources.

  const dispose = disposer()
  
  dispose.schedule(() => console.log("dispose 1"))
  dispose.schedule(() => console.log("dispose 2"))
  dispose.schedule(cycle(myGameloop))
  dispose.schedule(ev(window, {keydown: myKeydown}))
  
  dispose() // dispose everything backwards
    // *dispose ev*
    // *dispose cycle*
    // "dispose 2"
    // "dispose 1"

  more disposer tricks.

  const myThing = dispose.own(new MyThing(), t => t.dispose())
    // create a thing and schedule its dispose

  const myThing = dispose.disposable(new MyThing())
    // return and schedule a Disposable thing

  const {dispose, schedule, own, disposable} = disposer()
  
  schedule(cycle(myGameloop))
  const myThing = disposable(new MyThing)
  
  dispose()

🎲 rand

• Rand — random utility.

  const rand = new Rand(Math.random)

  const rand = new Rand(mulberry(123))
    // seeded pseudo-random number generator

  rand.u32() // get a random unsigned 32-bit integer.
    // 3286174905
  
  rand.roll(0.25) // 25% chance of true.
    // false
  
  rand.range(10, 20) // random float between two numbers.
    // 14.8591238
  
  rand.integerRange(1, 6) // inclusive integer range.
    // 4
  
  rand.index(7) // given array length, pick an array index.
    // 5
  
  rand.pick(["a", "b", "c"]) // pick your poison.
    // "c"
  
  rand.select(2, ["a", "b", "c"]) // pick multiple.
    // ["a", "c"]
  
  rand.yoink(["a", "b", "c"]) // remove and return one array element.
    // "a"
  
  rand.extract(2, ["a", "b", "c"]) // yoink multiple.
    // ["b", "c"]
  
  rand.shuffle(["a", "b", "c"]) // random-sort array in-place.
    // ["c", "a", "b"]

• mulberry — seeded pseudo-random number generator.

  const random = mulberry(123)
  
  random()
    // 0.7872516233474016
  
  random()
    // 0.1785435655619949

• rand32 — crypto-random unsigned 32-bit integer.

  rand32()
    // 3948271056

• hash32 — mix entropy into a 32-bit integer (fast, non-cryptographic).

  hash32(123, "hello", 234, "world")
    // 1012994381

✅ ok, err, result

• ok — Ok<Value> — indicate success.

  ok(123)
    // {ok: true, value: 123}

• err — Err<E> — indicate failure.

  err("fail")
    // {ok: false, error: "fail"}

• Result<Value, E> — indicate something might succeed or fail.

  let result: Result<number, "fail"> = ok(123)
  
  result = err("fail")

• getOk/getErr — get the value, or undefined.

  getOk(ok(123)) // 123
  getOk(err("fail")) // undefined
  
  getErr(ok(123)) // undefined
  getErr(err("fail")) // "fail"

• gotOk/gotErr — get the value, or throw.

  gotOk(ok(123)) // 123
  gotOk(err("fail")) // throws Error("fail")
  
  gotErr(ok(123)) // throws error
  gotErr(err("fail")) // "fail"

🧬 hex and more

• hex — encode/decode hexadecimal data.

  hex(bytes) // encode Uint8Array bytes to string.
  hex.toBytes(string) // decode string to bytes.
  hex.toInteger(string) // decode string as integer.
  hex.fromInteger(n) // encode integer as a string.
  hex.random(32) // generate random encoded string, 32 bytes.

  // we have more than just hex.
  hex(bytes) // string
  base2(bytes) // string
  base36(bytes) // string
  base58(bytes) // string
  base62(bytes) // string
  base64(bytes) // string
  base64url(bytes) // string

• txt — text data.

  txt(bytes) // convert utf8 bytes to string.
  txt.toBytes("hello") // convert string to utf8 bytes.

• bytes — uint8array utilities.

  bytes.eq(bytesA, bytesB) // true if they're equal.
  bytes.random(32) // get 32 crypto-random bytes.

🧑‍💻 https://e280.org/