import { distinctUntilChanged } from './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, * using a property accessed by using the key provided to check if the two items are distinct. * * 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 An example comparing the name of persons * * interface Person { * age: number, * name: string * } * * Observable.of( * { age: 4, name: 'Foo'}, * { age: 7, name: 'Bar'}, * { age: 5, name: 'Foo'}, * { age: 6, name: 'Foo'}) * .distinctUntilKeyChanged('name') * .subscribe(x => console.log(x)); * * // displays: * // { age: 4, name: 'Foo' } * // { age: 7, name: 'Bar' } * // { age: 5, name: 'Foo' } * * @example An example comparing the first letters of the name * * interface Person { * age: number, * name: string * } * * Observable.of( * { age: 4, name: 'Foo1'}, * { age: 7, name: 'Bar'}, * { age: 5, name: 'Foo2'}, * { age: 6, name: 'Foo3'}) * .distinctUntilKeyChanged('name', (x: string, y: string) => x.substring(0, 3) === y.substring(0, 3)) * .subscribe(x => console.log(x)); * * // displays: * // { age: 4, name: 'Foo1' } * // { age: 7, name: 'Bar' } * // { age: 5, name: 'Foo2' } * * @see {@link distinct} * @see {@link distinctUntilChanged} * * @param {string} key String key for object property lookup on each item. * @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 based on the key specified. * @method distinctUntilKeyChanged * @owner Observable */ export function distinctUntilKeyChanged(key, compare) { return distinctUntilChanged((x, y) => compare ? compare(x[key], y[key]) : x[key] === y[key]); } //# sourceMappingURL=distinctUntilKeyChanged.js.map