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node_modules/rxjs/operators/pairwise.d.ts

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+import { OperatorFunction } from '../interfaces';
+/**
+ * Groups pairs of consecutive emissions together and emits them as an array of
+ * two values.
+ *
+ * <span class="informal">Puts the current value and previous value together as
+ * an array, and emits that.</span>
+ *
+ * <img src="./img/pairwise.png" width="100%">
+ *
+ * The Nth emission from the source Observable will cause the output Observable
+ * to emit an array [(N-1)th, Nth] of the previous and the current value, as a
+ * pair. For this reason, `pairwise` emits on the second and subsequent
+ * emissions from the source Observable, but not on the first emission, because
+ * there is no previous value in that case.
+ *
+ * @example <caption>On every click (starting from the second), emit the relative distance to the previous click</caption>
+ * var clicks = Rx.Observable.fromEvent(document, 'click');
+ * var pairs = clicks.pairwise();
+ * var distance = pairs.map(pair => {
+ *   var x0 = pair[0].clientX;
+ *   var y0 = pair[0].clientY;
+ *   var x1 = pair[1].clientX;
+ *   var y1 = pair[1].clientY;
+ *   return Math.sqrt(Math.pow(x0 - x1, 2) + Math.pow(y0 - y1, 2));
+ * });
+ * distance.subscribe(x => console.log(x));
+ *
+ * @see {@link buffer}
+ * @see {@link bufferCount}
+ *
+ * @return {Observable<Array<T>>} An Observable of pairs (as arrays) of
+ * consecutive values from the source Observable.
+ * @method pairwise
+ * @owner Observable
+ */
+export declare function pairwise<T>(): OperatorFunction<T, [T, T]>;