Code snippets

filter-constructor.ts

const arr = [new Date(), new RegExp(''), new String('test'), 'test', /test/, new Number(1), 1, BigInt(1), 1n]

type InferConstructorType<C> = C extends DateConstructor ? Date : C extends ((...args: any[]) => infer T) | (new (...args: any[]) => infer T) ?
  T : unknown

function filterInstance<Constructor extends ((...args: any[]) => any) | (new (...args: any[]) => any)>(
  t: Constructor
) {
  return (item: any, _index: number, _arr: any[]): item is InferConstructorType<Constructor> => {
    if (typeof item === 'object') {
      return item instanceof t
    }
    // for literal
    return item.constructor === t
  }
}

const regexps = arr.filter(filterInstance(RegExp))

const strings = arr.filter(filterInstance(String))

const numbers = arr.filter(filterInstance(Number))

const bigints = arr.filter(filterInstance(BigInt))

const dates = arr.filter(filterInstance(Date))

confusion thing, why did DateConstructor has (): string? Is there any constructor built-in that has the same thing?

for new() was one type, but for () was another type, not like String (): string and new (): String that can handler universally