@reactivex/rxjs/dist/amd/operator/pairwise.js

Reactive Extensions for modern JavaScript

var __extends = (this && this.__extends) || function (d, b) {
    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
    function __() { this.constructor = d; }
    d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
define(["require", "exports", '../Subscriber'], function (require, exports, Subscriber_1) {
    "use strict";
    /**
     * Returns a new observable that triggers on the second and following inputs.
     * An input that triggers an event will return an pair of [(N - 1)th, Nth].
     * The (N-1)th is stored in the internal state until Nth input occurs.
     *
     * <img src="./img/pairwise.png" width="100%">
     *
     * @return {Observable<R>} an observable of pairs of values.
     * @method pairwise
     * @owner Observable
     */
    function pairwise() {
        return this.lift(new PairwiseOperator());
    }
    exports.pairwise = pairwise;
    var PairwiseOperator = (function () {
        function PairwiseOperator() {
        }
        PairwiseOperator.prototype.call = function (subscriber, source) {
            return source._subscribe(new PairwiseSubscriber(subscriber));
        };
        return PairwiseOperator;
    }());
    /**
     * We need this JSDoc comment for affecting ESDoc.
     * @ignore
     * @extends {Ignored}
     */
    var PairwiseSubscriber = (function (_super) {
        __extends(PairwiseSubscriber, _super);
        function PairwiseSubscriber(destination) {
            _super.call(this, destination);
            this.hasPrev = false;
        }
        PairwiseSubscriber.prototype._next = function (value) {
            if (this.hasPrev) {
                this.destination.next([this.prev, value]);
            }
            else {
                this.hasPrev = true;
            }
            this.prev = value;
        };
        return PairwiseSubscriber;
    }(Subscriber_1.Subscriber));
});
//# sourceMappingURL=pairwise.js.map