Simple fuzzy searching algorithm

fuzzySearch.ts

/**
 * A fuzzy match algorithm.
 * @param {string} needle the string to search for
 * @param {string} haystack the string to search in
 */
export function fuzzyMatch(needle: string = "", haystack: string = "") {
	const haystackLen = haystack.length;
	const needleLength = needle.length;

	needle = needle.toLowerCase();
	haystack = haystack.toLowerCase();

	// needle is too long to contain haystack
	if (needleLength > haystackLen) {
		return false;
	}

	// needle is either haystack or not a match.
	if (needleLength === haystackLen) {
		return needle === haystack;
	}

	return needle.split("").every(function (n) {
		const needleChar = n.charCodeAt(0);
		let j = 0;

		while (j < haystackLen) {
			if (haystack.charCodeAt(j++) === needleChar) {
				return true;
			}
		}

		return false;
	});
}

/**
 * Fuzzy searching an array of fields.
 */
export function fuzzySearch<Field extends Object>(fields: Field[], searchableFields: Array<keyof Partial<Field>> = []) {
	const fieldsIndex = fields.map((field) => {
		var fieldIndex = "";

		for (let i = 0; i < searchableFields.length; i++) {
			let fieldKey = searchableFields[i];
			if (typeof field[fieldKey] === "string") {
				fieldIndex += `${field[fieldKey]}|`;
			}
		}

		return fieldIndex;
	});

	return function search(search: string): Field[] {
		let searchResults = [];

		for (let i = 0; i < fieldsIndex.length; i++) {
			if (fuzzyMatch(search, fieldsIndex[i])) {
				searchResults.push(fields[i]);
			}
		}

		return searchResults;
	};
}