fromEventPattern.js
926 Bytes
import { Observable } from '../Observable';
import { isArray } from '../util/isArray';
import { isFunction } from '../util/isFunction';
import { map } from '../operators/map';
export function fromEventPattern(addHandler, removeHandler, resultSelector) {
if (resultSelector) {
return fromEventPattern(addHandler, removeHandler).pipe(map(args => isArray(args) ? resultSelector(...args) : resultSelector(args)));
}
return new Observable(subscriber => {
const handler = (...e) => subscriber.next(e.length === 1 ? e[0] : e);
let retValue;
try {
retValue = addHandler(handler);
}
catch (err) {
subscriber.error(err);
return undefined;
}
if (!isFunction(removeHandler)) {
return undefined;
}
return () => removeHandler(handler, retValue);
});
}
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