Binary Search

binarySearch()

Performs a binary search on a sorted array using a custom key selector function.

Signature

binarySearch(
  sorted: T[],
  matcher: string | number,
  keySelector: (item: T) => string | number,
  caseInsensitive: boolean
): T | undefined

Parameters

Parameter	Type	Description
sorted	T[]	Pre-sorted array to search
matcher	string | number	Value to search for
keySelector	(item: T) => string | number	Function to extract comparison key from items
caseInsensitive	boolean	Whether to ignore case for string comparisons

Returns

T | undefined - First matching item found, or undefined if not found

Description

This method implements a binary search algorithm with the following characteristics:

• Works on pre-sorted arrays
• Supports both string and numeric keys
• Optional case-insensitive string comparison
• Returns first match found
• O(log n) time complexity

Example

const products = [
  { id: 1, name: "Laptop" },
  { id: 2, name: "Phone" },
  { id: 3, name: "Tablet" }
];

const finder = new Finder(products);
const result = finder.binarySearch(
  products, 
  "phone",
  (p) => p.name,
  true
);
// Returns { id: 2, name: "Phone" }

Performance

Metric	Value
Time Complexity	O(log n)
Space Complexity	O(1)
Best Case	O(1)
Worst Case	O(log n)

Use Cases

• Searching large sorted datasets
• Implementing fast lookup for static data
• Optimizing search performance for read-heavy applications