@reactivex/rxjs
Version:
Reactive Extensions for modern JavaScript
70 lines • 3.15 kB
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', '../util/ArgumentOutOfRangeError'], function (require, exports, Subscriber_1, ArgumentOutOfRangeError_1) {
"use strict";
/**
* Returns an Observable that emits the item at the specified index in the source Observable.
* If default is given, missing indices will output this value on next; otherwise, outputs error.
* @throws {ArgumentOutOfRangeError} When using `elementAt(i)`, it delivers an
* ArgumentOutOrRangeError to the Observer's `error` callback if `i < 0` or the
* Observable has completed before emitting the i-th `next` notification.
* @param {number} index the index of the value to be retrieved.
* @param {any} [defaultValue] the default value returned for missing indices.
* @return {Observable} an Observable that emits a single item, if it is found. Otherwise, will emit the default value if given.
* @method elementAt
* @owner Observable
*/
function elementAt(index, defaultValue) {
return this.lift(new ElementAtOperator(index, defaultValue));
}
exports.elementAt = elementAt;
var ElementAtOperator = (function () {
function ElementAtOperator(index, defaultValue) {
this.index = index;
this.defaultValue = defaultValue;
if (index < 0) {
throw new ArgumentOutOfRangeError_1.ArgumentOutOfRangeError;
}
}
ElementAtOperator.prototype.call = function (subscriber, source) {
return source._subscribe(new ElementAtSubscriber(subscriber, this.index, this.defaultValue));
};
return ElementAtOperator;
}());
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
var ElementAtSubscriber = (function (_super) {
__extends(ElementAtSubscriber, _super);
function ElementAtSubscriber(destination, index, defaultValue) {
_super.call(this, destination);
this.index = index;
this.defaultValue = defaultValue;
}
ElementAtSubscriber.prototype._next = function (x) {
if (this.index-- === 0) {
this.destination.next(x);
this.destination.complete();
}
};
ElementAtSubscriber.prototype._complete = function () {
var destination = this.destination;
if (this.index >= 0) {
if (typeof this.defaultValue !== 'undefined') {
destination.next(this.defaultValue);
}
else {
destination.error(new ArgumentOutOfRangeError_1.ArgumentOutOfRangeError);
}
}
destination.complete();
};
return ElementAtSubscriber;
}(Subscriber_1.Subscriber));
});
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