Debounce data based on a key or value

debounceDistinct.js

Rx.Observable.prototype.debounceDistinct = function debounceDistinct(delay, keySelector = value => value) {
  var source = this;

  return Rx.Observable.create((observer) => {
    const allKeys = {};

    function reinitDelayFor(key) {
      allKeys[key] = false;
      setTimeout(() => allKeys[key] = true, delay);
    }

    return source.subscribe(
      function (data) {
        try {
          const key = keySelector(data);
          if (!allKeys.hasOwnProperty(key)) {
            reinitDelayFor(key);
          }
          
          const shouldPass = allKeys[key];
          if (shouldPass) {
            observer.onNext(data);
            reinitDelayFor(key);
          }
        } catch (e) {
          observer.onError(e);
        }
      },
      observer.onError.bind(observer),
      observer.onCompleted.bind(observer)
    );
  });
};