es6/MiscJSDoc.js
import { Observable } from './Observable';
import './observable/dom/MiscJSDoc';
/**
* We need this JSDoc comment for affecting ESDoc.
* @extends {Ignored}
* @hide true
*/
export class ObservableDoc {
/**
* Creates a new Observable, that will execute the specified function when an
* {@link Observer} subscribes to it.
*
* <span class="informal">Create custom Observable, that does whatever you like.</span>
*
* <img src="./img/create.png" width="100%">
*
* `create` converts an `onSubscription` function to an actual Observable.
* Whenever someone subscribes to that Observable, the function will be called
* with an {@link Observer} instance as a first and only parameter. `onSubscription` should
* then invoke the Observers `next`, `error` and `complete` methods.
*
* Calling `next` with a value will emit that value to the observer. Calling `complete`
* means that Observable finished emitting and will not do anything else.
* Calling `error` means that something went wrong - value passed to `error` method should
* provide details on what exactly happened.
*
* A well-formed Observable can emit as many values as it needs via `next` method,
* but `complete` and `error` methods can be called only once and nothing else can be called
* thereafter. If you try to invoke `next`, `complete` or `error` methods after created
* Observable already completed or ended with an error, these calls will be ignored to
* preserve so called *Observable Contract*. Note that you are not required to call
* `complete` at any point - it is perfectly fine to create an Observable that never ends,
* depending on your needs.
*
* `onSubscription` can optionally return either a function or an object with
* `unsubscribe` method. In both cases function or method will be called when
* subscription to Observable is being cancelled and should be used to clean up all
* resources. So, for example, if you are using `setTimeout` in your custom
* Observable, when someone unsubscribes, you can clear planned timeout, so that
* it does not fire needlessly and browser (or other environment) does not waste
* computing power on timing event that no one will listen to anyways.
*
* Most of the times you should not need to use `create`, because existing
* operators allow you to create an Observable for most of the use cases.
* That being said, `create` is low-level mechanism allowing you to create
* any Observable, if you have very specific needs.
*
* **TypeScript signature issue**
*
* Because Observable extends class which already has defined static `create` function,
* but with different type signature, it was impossible to assign proper signature to
* `Observable.create`. Because of that, it has very general type `Function` and thus
* function passed to `create` will not be type checked, unless you explicitly state
* what signature it should have.
*
* When using TypeScript we recommend to declare type signature of function passed to
* `create` as `(observer: Observer) => TeardownLogic`, where {@link Observer}
* and {@link TeardownLogic} are interfaces provided by the library.
*
* @example <caption>Emit three numbers, then complete.</caption>
* var observable = Rx.Observable.create(function (observer) {
* observer.next(1);
* observer.next(2);
* observer.next(3);
* observer.complete();
* });
* observable.subscribe(
* value => console.log(value),
* err => {},
* () => console.log('this is the end')
* );
*
* // Logs
* // 1
* // 2
* // 3
* // "this is the end"
*
*
* @example <caption>Emit an error</caption>
* const observable = Rx.Observable.create((observer) => {
* observer.error('something went really wrong...');
* });
*
* observable.subscribe(
* value => console.log(value), // will never be called
* err => console.log(err),
* () => console.log('complete') // will never be called
* );
*
* // Logs
* // "something went really wrong..."
*
*
* @example <caption>Return unsubscribe function</caption>
*
* const observable = Rx.Observable.create(observer => {
* const id = setTimeout(() => observer.next('...'), 5000); // emit value after 5s
*
* return () => { clearTimeout(id); console.log('cleared!'); };
* });
*
* const subscription = observable.subscribe(value => console.log(value));
*
* setTimeout(() => subscription.unsubscribe(), 3000); // cancel subscription after 3s
*
* // Logs:
* // "cleared!" after 3s
*
* // Never logs "..."
*
*
* @see {@link empty}
* @see {@link never}
* @see {@link of}
* @see {@link throw}
*
* @param {function(observer: Observer): TeardownLogic} onSubscription A
* function that accepts an Observer, and invokes its `next`,
* `error`, and `complete` methods as appropriate, and optionally returns some
* logic for cleaning up resources.
* @return {Observable} An Observable that, whenever subscribed, will execute the
* specified function.
* @static true
* @name create
* @owner Observable
*/
static create(onSubscription) {
return new Observable(onSubscription);
}
;
}
/**
* An interface for a consumer of push-based notifications delivered by an
* {@link Observable}.
*
* ```ts
* interface Observer<T> {
* closed?: boolean;
* next: (value: T) => void;
* error: (err: any) => void;
* complete: () => void;
* }
* ```
*
* An object conforming to the Observer interface is usually
* given to the `observable.subscribe(observer)` method, and the Observable will
* call the Observer's `next(value)` method to provide notifications. A
* well-behaved Observable will call an Observer's `complete()` method exactly
* once or the Observer's `error(err)` method exactly once, as the last
* notification delivered.
*
* @interface
* @name Observer
* @noimport true
*/
export class ObserverDoc {
constructor() {
/**
* An optional flag to indicate whether this Observer, when used as a
* subscriber, has already been unsubscribed from its Observable.
* @type {boolean}
*/
this.closed = false;
}
/**
* The callback to receive notifications of type `next` from the Observable,
* with a value. The Observable may call this method 0 or more times.
* @param {T} value The `next` value.
* @return {void}
*/
next(value) {
return void 0;
}
/**
* The callback to receive notifications of type `error` from the Observable,
* with an attached {@link Error}. Notifies the Observer that the Observable
* has experienced an error condition.
* @param {any} err The `error` exception.
* @return {void}
*/
error(err) {
return void 0;
}
/**
* The callback to receive a valueless notification of type `complete` from
* the Observable. Notifies the Observer that the Observable has finished
* sending push-based notifications.
* @return {void}
*/
complete() {
return void 0;
}
}
/**
* `SubscribableOrPromise` interface describes values that behave like either
* Observables or Promises. Every operator that accepts arguments annotated
* with this interface, can be also used with parameters that are not necessarily
* RxJS Observables.
*
* Following types of values might be passed to operators expecting this interface:
*
* ## Observable
*
* RxJS {@link Observable} instance.
*
* ## Observable-like (Subscribable)
*
* This might be any object that has `Symbol.observable` method. This method,
* when called, should return object with `subscribe` method on it, which should
* behave the same as RxJS `Observable.subscribe`.
*
* `Symbol.observable` is part of https://github.com/tc39/proposal-observable proposal.
* Since currently it is not supported natively, and every symbol is equal only to itself,
* you should use https://github.com/blesh/symbol-observable polyfill, when implementing
* custom Observable-likes.
*
* **TypeScript Subscribable interface issue**
*
* Although TypeScript interface claims that Subscribable is an object that has `subscribe`
* method declared directly on it, passing custom objects that have `subscribe`
* method but not `Symbol.observable` method will fail at runtime. Conversely, passing
* objects with `Symbol.observable` but without `subscribe` will fail at compile time
* (if you use TypeScript).
*
* TypeScript has problem supporting interfaces with methods defined as symbol
* properties. To get around that, you should implement `subscribe` directly on
* passed object, and make `Symbol.observable` method simply return `this`. That way
* everything will work as expected, and compiler will not complain. If you really
* do not want to put `subscribe` directly on your object, you will have to type cast
* it to `any`, before passing it to an operator.
*
* When this issue is resolved, Subscribable interface will only permit Observable-like
* objects with `Symbol.observable` defined, no matter if they themselves implement
* `subscribe` method or not.
*
* ## ES6 Promise
*
* Promise can be interpreted as Observable that emits value and completes
* when it is resolved or errors when it is rejected.
*
* ## Promise-like (Thenable)
*
* Promises passed to operators do not have to be native ES6 Promises.
* They can be implementations from popular Promise libraries, polyfills
* or even custom ones. They just need to have `then` method that works
* as the same as ES6 Promise `then`.
*
* @example <caption>Use merge and then map with non-RxJS observable</caption>
* const nonRxJSObservable = {
* subscribe(observer) {
* observer.next(1000);
* observer.complete();
* },
* [Symbol.observable]() {
* return this;
* }
* };
*
* Rx.Observable.merge(nonRxJSObservable)
* .map(value => "This value is " + value)
* .subscribe(result => console.log(result)); // Logs "This value is 1000"
*
*
* @example <caption>Use combineLatest with ES6 Promise</caption>
* Rx.Observable.combineLatest(Promise.resolve(5), Promise.resolve(10), Promise.resolve(15))
* .subscribe(
* value => console.log(value),
* err => {},
* () => console.log('the end!')
* );
* // Logs
* // [5, 10, 15]
* // "the end!"
*
*
* @interface
* @name SubscribableOrPromise
* @noimport true
*/
export class SubscribableOrPromiseDoc {
}
/**
* `ObservableInput` interface describes all values that are either an
* {@link SubscribableOrPromise} or some kind of collection of values that
* can be transformed to Observable emitting that values. Every operator that
* accepts arguments annotated with this interface, can be also used with
* parameters that are not necessarily RxJS Observables.
*
* `ObservableInput` extends {@link SubscribableOrPromise} with following types:
*
* ## Array
*
* Arrays can be interpreted as observables that emit all values in array one by one,
* from left to right, and then complete immediately.
*
* ## Array-like
*
* Arrays passed to operators do not have to be built-in JavaScript Arrays. They
* can be also, for example, `arguments` property available inside every function,
* [DOM NodeList](https://developer.mozilla.org/pl/docs/Web/API/NodeList),
* or, actually, any object that has `length` property (which is a number)
* and stores values under non-negative (zero and up) integers.
*
* ## ES6 Iterable
*
* Operators will accept both built-in and custom ES6 Iterables, by treating them as
* observables that emit all its values in order of iteration and then complete
* when iteration ends. Note that contrary to arrays, Iterables do not have to
* necessarily be finite, so creating Observables that never complete is possible as well.
*
* Note that you can make iterator an instance of Iterable by having it return itself
* in `Symbol.iterator` method. It means that every operator accepting Iterables accepts,
* though indirectly, iterators themselves as well. All native ES6 iterators are instances
* of Iterable by default, so you do not have to implement their `Symbol.iterator` method
* yourself.
*
* **TypeScript Iterable interface issue**
*
* TypeScript `ObservableInput` interface actually lacks type signature for Iterables,
* because of issues it caused in some projects (see [this issue](https://github.com/ReactiveX/rxjs/issues/2306)).
* If you want to use Iterable as argument for operator, cast it to `any` first.
* Remember of course that, because of casting, you have to yourself ensure that passed
* argument really implements said interface.
*
*
* @example <caption>Use merge with arrays</caption>
* Rx.Observable.merge([1, 2], [4], [5, 6])
* .subscribe(
* value => console.log(value),
* err => {},
* () => console.log('ta dam!')
* );
*
* // Logs
* // 1
* // 2
* // 3
* // 4
* // 5
* // 6
* // "ta dam!"
*
*
* @example <caption>Use merge with array-like</caption>
* Rx.Observable.merge({0: 1, 1: 2, length: 2}, {0: 3, length: 1})
* .subscribe(
* value => console.log(value),
* err => {},
* () => console.log('nice, huh?')
* );
*
* // Logs
* // 1
* // 2
* // 3
* // "nice, huh?"
*
* @example <caption>Use merge with an Iterable (Map)</caption>
* const firstMap = new Map([[1, 'a'], [2, 'b']]);
* const secondMap = new Map([[3, 'c'], [4, 'd']]);
*
* Rx.Observable.merge(
* firstMap, // pass Iterable
* secondMap.values() // pass iterator, which is itself an Iterable
* ).subscribe(
* value => console.log(value),
* err => {},
* () => console.log('yup!')
* );
*
* // Logs
* // [1, "a"]
* // [2, "b"]
* // "c"
* // "d"
* // "yup!"
*
* @example <caption>Use from with generator (returning infinite iterator)</caption>
* // infinite stream of incrementing numbers
* const infinite = function* () {
* let i = 0;
*
* while (true) {
* yield i++;
* }
* };
*
* Rx.Observable.from(infinite())
* .take(3) // only take 3, cause this is infinite
* .subscribe(
* value => console.log(value),
* err => {},
* () => console.log('ta dam!')
* );
*
* // Logs
* // 0
* // 1
* // 2
* // "ta dam!"
*
* @interface
* @name ObservableInput
* @noimport true
*/
export class ObservableInputDoc {
}
/**
*
* This interface describes what should be returned by function passed to Observable
* constructor or static {@link create} function. Value of that interface will be used
* to cancel subscription for given Observable.
*
* `TeardownLogic` can be:
*
* ## Function
*
* Function that takes no parameters. When consumer of created Observable calls `unsubscribe`,
* that function will be called
*
* ## AnonymousSubscription
*
* `AnonymousSubscription` is simply an object with `unsubscribe` method on it. That method
* will work the same as function
*
* ## void
*
* If created Observable does not have any resources to clean up, function does not have to
* return anything.
*
* @interface
* @name TeardownLogic
* @noimport true
*/
export class TeardownLogicDoc {
}
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