import { reduce } from './reduce';
|
import { MonoTypeOperatorFunction } from '../types';
|
import { isFunction } from '../util/isFunction';
|
|
/**
|
* The Max operator operates on an Observable that emits numbers (or items that can be compared with a provided function),
|
* and when source Observable completes it emits a single item: the item with the largest value.
|
*
|
* 
|
*
|
* ## Examples
|
*
|
* Get the maximal value of a series of numbers
|
*
|
* ```ts
|
* import { of, max } from 'rxjs';
|
*
|
* of(5, 4, 7, 2, 8)
|
* .pipe(max())
|
* .subscribe(x => console.log(x));
|
*
|
* // Outputs
|
* // 8
|
* ```
|
*
|
* Use a comparer function to get the maximal item
|
*
|
* ```ts
|
* import { of, max } from 'rxjs';
|
*
|
* of(
|
* { age: 7, name: 'Foo' },
|
* { age: 5, name: 'Bar' },
|
* { age: 9, name: 'Beer' }
|
* ).pipe(
|
* max((a, b) => a.age < b.age ? -1 : 1)
|
* )
|
* .subscribe(x => console.log(x.name));
|
*
|
* // Outputs
|
* // 'Beer'
|
* ```
|
*
|
* @see {@link min}
|
*
|
* @param {Function} [comparer] - Optional comparer function that it will use instead of its default to compare the
|
* value of two items.
|
* @return A function that returns an Observable that emits item with the
|
* largest value.
|
*/
|
export function max<T>(comparer?: (x: T, y: T) => number): MonoTypeOperatorFunction<T> {
|
return reduce(isFunction(comparer) ? (x, y) => (comparer(x, y) > 0 ? x : y) : (x, y) => (x > y ? x : y));
|
}
|
