README.md

count-of

Count array / list occurrences... 😐

const arr = Array.from(
  { length: 10 },
  () => Math.round(Math.random() * 5)
);
countOf(3, arr);

API

countOf(reference, target)

Searchable is a barebones ArrayLike interface that has the methods it needs to forfill its task.

• This is to permit the use of a string as a native target - ArrayLike<T> would not have permitted this.

• reference: T - The search term or element.
• target: Searchable<T> - The entity to search.

Notes

• This implementation derives from underscore and lodash but focusing on one element as the query focus.
• Attempts were made to allow it to accept a function, and then build the string search predicate from there... but that fell short rapidly - and it was not worth investing more time into something that is ultimately slower than the best available native solution.

---

You can find more of my shenanigans projects with TinkerStorm... might be more interesting, ya never know. 🤷‍♂️

count-of.ts

interface Searchable<T> {
	length: number;
	includes(searchElement: T, fromIndex?: number): boolean
	indexOf(searchElement: T, fromIndex?: number): number
}

function countOf<T>(reference: T, target: Searchable<T>) {
	// failover, no occurances found
	if (!target.includes(reference)) {
		return 0;
	}

	let occurrences = 0;
	let lastIndex = 0;

	function incrementCount(index) {
		lastIndex = index + 1;
		occurrences++;
	}

	while (lastIndex < target.length || occurances <= 0) {
		const index = target.indexOf(reference, lastIndex);

		if (index < 0) break;

		incrementCount(index);
	}

	return occurrences;
}