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Find One

findOne()​

Finds the first item matching specified criteria using optimized search strategies.

Signature​

findOne(
  matcher: string | number,
  keySelector: KeySelector<T>,
  options?: FindOptions<T>
): T | undefined

Type Definitions​

FindOptions<T>​

interface FindOptions<T extends GenericObject = {}> {
  /** Enables fuzzy matching when exact match fails */
  fuzzy?: boolean;
  /** Key for caching the result */
  cacheKey?: string;
  /** Forces binary search regardless of dataset size */
  forceBinary?: boolean;
  /** Enables case-insensitive string matching */
  caseInsensitive?: boolean;
  /** Controls automatic array sorting */
  needSorting?: boolean;
  /** Alternate data source override */
  data?: T[] | (() => T[]);
}

KeySelector<T>​

/**
 * Defines how to extract keys from items
 * Can be:
 * - A string/number property name
 * - A function that extracts key from item
 */
type KeySelector<T> = Extract<OwnKeys<T>, string | number> | ((item: T) => string | number);

type OwnKeys<T> = { [K in keyof T]: {} extends Pick<T, K> ? never : K;}[keyof T];

Parameters​

ParameterTypeDescription
matcherstring | numberValue to match against
keySelectorKeySelector<T>Property name or value extractor function
optionsFindOptions<T>Search configuration

Returns​

T | undefined - First matching item or undefined if none found

Use Cases​

Basic Usage​

const userFinder = new Finder(users);
const admin = userFinder.findOne('admin@example.com', 'email');

With Options​

const productFinder = new Finder(products);
const laptop = productFinder.findOne('laptop', 'category', {
  fuzzy: true,
  caseInsensitive: false
});
const result = userFinder.findOne('john', 'name', {
  cacheKey: 'john-search'
});

Behavior Details​

  1. Cache First: Checks cache if cacheKey provided
  2. Search Strategies:
    • Linear search for small datasets (less than 100 items)
    • Binary search for larger sorted datasets
    • Fuzzy search when enabled and no exact match
  3. Result Caching: Stores successful finds when cacheKey specified

Notes​

  1. Performance Considerations:

    • Uses cache when available (O(1) lookup)
    • Falls back to linear search for small datasets (O(n))
    • Uses binary search for large sorted datasets (O(log n))
    • Fuzzy search is O(n) when enabled

  2. Cache Behavior:

    • Cache entries expire after 5 minutes by default
    • Cache key can be customized via cacheKey option
    • Cache is automatically cleared when data changes

  3. String Matching:

    • Case insensitive by default
    • Uses exact matching when fuzzy is false
    • Supports fuzzy matching when fuzzy is true

  4. Sorting:

    • Sorts data automatically when needSorting is true
    • Skips sorting when data is already sorted

  5. Edge Cases:

    • Returns undefined for empty datasets
    • Handles null/undefined values in data
    • Works with both string and numeric keys

See Also​