Function Utilities

Quick Reference

• assert
• compare
• compareBy
• compose
• partial
• constant
• curry
• debounce
• identity
• memo
• negate
• once
• pipe
• tap
• throttle

Common Patterns

import {
  assert,
  compareBy,
  compose,
  constant,
  curry,
  debounce,
  identity,
  memo,
  negate,
  and,
  once,
  partial,
  pipe,
  tap,
  throttle,
} from '@vielzeug/toolkit';

assert(Array.isArray([1, 2, 3]), 'Expected array');

const sortUsers = compareBy<{ name: string; age: number }>({ age: 'desc', name: 'asc' });

const trimUpper = pipe(
  (s: string) => s.trim(),
  (s) => s.toUpperCase(),
);

const trimUpperRtl = compose(
  (s: string) => s.toUpperCase(),
  (s: string) => s.trim(),
);

const add = (a: number, b: number) => a + b;
const curriedAdd = curry(add);

const double = partial((value: number, factor: number) => value * factor, 2);
const isWorkingAge = and<number>(
  (age) => age >= 18,
  (age) => age < 65,
);

const expensive = memo((n: number) => n * n);
const identityValue = identity('ok');
const alwaysFive = constant(5);
const odds = [1, 2, 3, 4].filter(negate((n: number) => n % 2 === 0));
const ratio = ((a: number, b: number) => a / b)(10, 2); // 5
const observed = tap(42, (value) => console.log('tap', value));
const initOnce = once(() => console.log('init'));
const onInput = debounce((q: string) => console.log(q), 250);
const onScroll = throttle(() => console.log('scroll'), 100);

console.log(
  sortUsers,
  trimUpper('  alice  '),
  trimUpperRtl('  alice  '),
  curriedAdd(2)(3),
  double(8),
  expensive(4),
  identityValue,
  alwaysFive(),
  odds,
  ratio,
  observed,
  isWorkingAge(32, 0, [32]),
  initOnce(),
  onInput,
  onScroll,
);