Get string ref counter

get-string-ref-counter.ts

export interface RefCounter<T = unknown> {
  getCount(item: T): number
  add(item: T): void
  remove(item: T): void
}

export const getStringRefCounter = (): RefCounter<string> => {
  const values: Record<string, number | undefined> = {}

  const getCount = (key: string): number => values[key] || 0

  return {
    getCount,

    add(key: string): void {
      values[key] = getCount(key) + 1
    },

    remove(key: string): void {
      const count = getCount(key)

      if (count) {
        if (count === 1) {
          delete values[key]
        } else {
          values[key] = count - 1
        }
      }
    },
  }
}