I have recently come across the version 4 of RxJS, and noticed that the method hasObservers on Subjects seems to have been removed. I am now faced with the challenge of migrating, as this removal is not documented on the migration guide.
hasObservers: function () { checkDisposed(this); return this.observers.length > 0; }
Is there an alternative solution to determine if a subject has a subscriber before calling next?
There doesn't appear to be a direct equivalent to this function in rxjs 5. However, you have the option to create your own version:
Subject.prototype.hasObservers = function checkObservers() {
if (this.closed) {
throw new ObjectUnsubscribedError();
}
return this.observers.length > 0;
};
Upon examining the source code, you can find how the observers array is explicitly defined. It is declared as a public property, allowing direct access to it:
import { Subject } from 'rxjs/Subject';
let s = new Subject();
s.subscribe(val => val);
s.subscribe(val => val);
console.log(s.observers.length > 0);
The output displayed will be true.
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