mirror of
https://github.com/fooflington/selfdefined.git
synced 2025-10-31 06:08:33 +00:00
42 lines
1.5 KiB
JavaScript
42 lines
1.5 KiB
JavaScript
|
"use strict";
|
||
|
|
var pairwise_1 = require('../operators/pairwise');
|
||
|
|
/**
|
||
|
|
* 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
|
||
|
|
*/
|
||
|
|
function pairwise() {
|
||
|
|
return pairwise_1.pairwise()(this);
|
||
|
|
}
|
||
|
|
exports.pairwise = pairwise;
|
||
|
|
//# sourceMappingURL=pairwise.js.map
|