work.suroh.tk/node_modules/rxjs/_esm2015/operator/distinctUntilChanged.js

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2019-12-02 12:22:45 +00:00
import { distinctUntilChanged as higherOrder } from '../operators/distinctUntilChanged';
/* tslint:enable:max-line-length */
/**
* Returns an Observable that emits all items emitted by the source Observable that are distinct by comparison from the previous item.
*
* If a comparator function is provided, then it will be called for each item to test for whether or not that value should be emitted.
*
* If a comparator function is not provided, an equality check is used by default.
*
* @example <caption>A simple example with numbers</caption>
* Observable.of(1, 1, 2, 2, 2, 1, 1, 2, 3, 3, 4)
* .distinctUntilChanged()
* .subscribe(x => console.log(x)); // 1, 2, 1, 2, 3, 4
*
* @example <caption>An example using a compare function</caption>
* interface Person {
* age: number,
* name: string
* }
*
* Observable.of<Person>(
* { age: 4, name: 'Foo'},
* { age: 7, name: 'Bar'},
* { age: 5, name: 'Foo'})
* { age: 6, name: 'Foo'})
* .distinctUntilChanged((p: Person, q: Person) => p.name === q.name)
* .subscribe(x => console.log(x));
*
* // displays:
* // { age: 4, name: 'Foo' }
* // { age: 7, name: 'Bar' }
* // { age: 5, name: 'Foo' }
*
* @see {@link distinct}
* @see {@link distinctUntilKeyChanged}
*
* @param {function} [compare] Optional comparison function called to test if an item is distinct from the previous item in the source.
* @return {Observable} An Observable that emits items from the source Observable with distinct values.
* @method distinctUntilChanged
* @owner Observable
*/
export function distinctUntilChanged(compare, keySelector) {
return higherOrder(compare, keySelector)(this);
}
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