"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
var operators_1 = require("rxjs/operators");
/* tslint:enable:max-line-length */
/**
* Emits only the first value (or the first value that meets some condition)
* emitted by the source Observable.
*
* Emits only the first value. Or emits only the first
* value that passes some test.
*
*
*
* If called with no arguments, `first` emits the first value of the source
* Observable, then completes. If called with a `predicate` function, `first`
* emits the first value of the source that matches the specified condition. It
* may also take a `resultSelector` function to produce the output value from
* the input value, and a `defaultValue` to emit in case the source completes
* before it is able to emit a valid value. Throws an error if `defaultValue`
* was not provided and a matching element is not found.
*
* @example
Emit only the first click that happens on the DOM
* var clicks = Rx.Observable.fromEvent(document, 'click');
* var result = clicks.first();
* result.subscribe(x => console.log(x));
*
* @example Emits the first click that happens on a DIV
* var clicks = Rx.Observable.fromEvent(document, 'click');
* var result = clicks.first(ev => ev.target.tagName === 'DIV');
* result.subscribe(x => console.log(x));
*
* @see {@link filter}
* @see {@link find}
* @see {@link take}
*
* @throws {EmptyError} Delivers an EmptyError to the Observer's `error`
* callback if the Observable completes before any `next` notification was sent.
*
* @param {function(value: T, index: number, source: Observable): boolean} [predicate]
* An optional function called with each item to test for condition matching.
* @param {T} [defaultValue] The default value emitted in case no valid value
* was found on the source.
* @return {Observable} An Observable of the first item that matches the
* condition.
* @method first
* @owner Observable
*/
function first() {
var args = [];
for (var _i = 0; _i < arguments.length; _i++) {
args[_i] = arguments[_i];
}
return operators_1.first.apply(void 0, args)(this);
}
exports.first = first;
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