rxjs/dist/esm5/internal/operators/distinctUntilChanged.js

Reactive Extensions for modern JavaScript

import { operate } from '../util/lift';
import { OperatorSubscriber } from './OperatorSubscriber';
export function distinctUntilChanged(compare, keySelector) {
    compare = compare !== null && compare !== void 0 ? compare : defaultCompare;
    return operate(function (source, subscriber) {
        var prev;
        var first = true;
        source.subscribe(new OperatorSubscriber(subscriber, function (value) {
            ((first && ((prev = value), 1)) || !compare(prev, (prev = keySelector ? keySelector(value) : value))) &&
                subscriber.next(value);
            first = false;
        }));
    });
}
function defaultCompare(a, b) {
    return a === b;
}
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