findKey

object

This method is like find except that it returns the key of the first element predicate returns truthy for instead of the element itself.

Try in Playground

Installation

Import

import { findKey } from '@tulx/utils';

Source Code

Implementation

/**
 * This method is like find except that it returns the key of the first element predicate returns truthy for instead of the element itself.
 *
 * @param object - The object to inspect.
 * @param predicate - The function invoked per iteration.
 * @returns Returns the key of the matched element, else undefined.
 *
 * @example
 * ```ts
 * const users = {
 *   'barney': { 'age': 36, 'active': true },
 *   'fred': { 'age': 40, 'active': false },
 *   'pebbles': { 'age': 1, 'active': true }
 * };
 * findKey(users, (o) => o.age < 40); // 'barney'
 * ```
 */
export function findKey<T>(
  object: Record<string, T>,
  predicate: (value: T, key: string, object: Record<string, T>) => boolean
): string | undefined {
  for (const key in object) {
    if (Object.prototype.hasOwnProperty.call(object, key)) {
      if (predicate(object[key], key, object)) {
        return key;
      }
    }
  }
  return undefined;
}

Example

import { findKey } from '@tulx/utils';

const users = {
'barney': { 'age': 36, 'active': true },
'fred': { 'age': 40, 'active': false },
'pebbles': { 'age': 1, 'active': true }
};
findKey(users, (o) => o.age < 40); // 'barney'

Related Functions

assign

Assigns own enumerable string keyed properties of source objects to the destination object.

assignIn

This method is like assign except that it iterates over own and inherited source properties.

assignInWith

This method is like assignIn except that it accepts customizer which is invoked to produce the assigned values.

assignWith

This method is like assign except that it accepts customizer which is invoked to produce the assigned values.

Creates an array of values corresponding to paths of object.

create

Creates an object that inherits from the prototype object.