@reactivex/rxjs
Version:
Reactive Extensions for modern JavaScript
118 lines • 4.46 kB
JavaScript
;
var __extends = (this && this.__extends) || (function () {
var extendStatics = function (d, b) {
extendStatics = Object.setPrototypeOf ||
({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
return extendStatics(d, b);
}
return function (d, b) {
extendStatics(d, b);
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
})();
Object.defineProperty(exports, "__esModule", { value: true });
var Subscriber_1 = require("../Subscriber");
/**
* Emits values emitted by the source Observable so long as each value satisfies
* the given `predicate`, and then completes as soon as this `predicate` is not
* satisfied.
*
* <span class="informal">Takes values from the source only while they pass the
* condition given. When the first value does not satisfy, it completes.</span>
*
* 
*
* `takeWhile` subscribes and begins mirroring the source Observable. Each value
* emitted on the source is given to the `predicate` function which returns a
* boolean, representing a condition to be satisfied by the source values. The
* output Observable emits the source values until such time as the `predicate`
* returns false, at which point `takeWhile` stops mirroring the source
* Observable and completes the output Observable.
*
* ## Example
* Emit click events only while the clientX property is greater than 200
* ```ts
* import { fromEvent } from 'rxjs';
* import { takeWhile } from 'rxjs/operators';
*
* const clicks = fromEvent(document, 'click');
* const result = clicks.pipe(takeWhile(ev => ev.clientX > 200));
* result.subscribe(x => console.log(x));
* ```
*
* @see {@link take}
* @see {@link takeLast}
* @see {@link takeUntil}
* @see {@link skip}
*
* @param {function(value: T, index: number): boolean} predicate A function that
* evaluates a value emitted by the source Observable and returns a boolean.
* Also takes the (zero-based) index as the second argument.
* @param {boolean} inclusive When set to `true` the value that caused
* `predicate` to return `false` will also be emitted.
* @return {Observable<T>} An Observable that emits the values from the source
* Observable so long as each value satisfies the condition defined by the
* `predicate`, then completes.
* @method takeWhile
* @owner Observable
*/
function takeWhile(predicate, inclusive) {
if (inclusive === void 0) { inclusive = false; }
return function (source) {
return source.lift(new TakeWhileOperator(predicate, inclusive));
};
}
exports.takeWhile = takeWhile;
var TakeWhileOperator = /** @class */ (function () {
function TakeWhileOperator(predicate, inclusive) {
this.predicate = predicate;
this.inclusive = inclusive;
}
TakeWhileOperator.prototype.call = function (subscriber, source) {
return source.subscribe(new TakeWhileSubscriber(subscriber, this.predicate, this.inclusive));
};
return TakeWhileOperator;
}());
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
var TakeWhileSubscriber = /** @class */ (function (_super) {
__extends(TakeWhileSubscriber, _super);
function TakeWhileSubscriber(destination, predicate, inclusive) {
var _this = _super.call(this, destination) || this;
_this.predicate = predicate;
_this.inclusive = inclusive;
_this.index = 0;
return _this;
}
TakeWhileSubscriber.prototype._next = function (value) {
var destination = this.destination;
var result;
try {
result = this.predicate(value, this.index++);
}
catch (err) {
destination.error(err);
return;
}
this.nextOrComplete(value, result);
};
TakeWhileSubscriber.prototype.nextOrComplete = function (value, predicateResult) {
var destination = this.destination;
if (Boolean(predicateResult)) {
destination.next(value);
}
else {
if (this.inclusive) {
destination.next(value);
}
destination.complete();
}
};
return TakeWhileSubscriber;
}(Subscriber_1.Subscriber));
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