/**
 * @packageDocumentation
 * @module Number
 */
import { OperatorFunction, Subscribable } from 'rxjs';
/**
 * Returns an Observable that emits a formatted string value from a source number using Number.toLocaleString with
 * optional formatting options provided by Intl.NumberFormat
 *
 * @category Formatting
 *
 * @param locales The locale or locales that the number is being formatted for
 * @param format Formatting of the string based on
 *   [Intl.NumberFormat](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/NumberFormat)
 *
 * @example Return a string with Dutch number formatting
 * ```ts
 * of(1000000).pipe(toLocaleString('nl-NL')).subscribe();
 * ```
 * Output: `'1.000.000'`
 *
 * @example Return a string with UK English number formatting
 * ```ts
 * of(1000000).pipe(toLocaleString('en-GB')).subscribe();
 * ```
 * Output: `'1,000,000'`
 *
 * @example Return a string with UK English number formatting and Euro currency style
 * ```ts
 * of(1000000).pipe(toLocaleString('en-GB', { currency: 'EUR', style: 'currency' })).subscribe();
 * ```
 * Output: `'€1,000,000.00'`
 *
 * @returns Observable that emits a formatted string from a source number
 */
export declare function toLocaleString(locales?: Subscribable<string | string[]> | string | string[], format?: Subscribable<Intl.NumberFormatOptions> | Intl.NumberFormatOptions): OperatorFunction<number, string>;