redux debounce middleware

debounce-middleware.ts

import { Dispatch } from "react";
import { AnyAction, Store } from "redux";
import { State } from "./types";

/**
 * Create a middleware that will debounce actions of a given kind.
 *
 * Debouncing means that if a certain action happens more than once in a given
 * period, only the last one will actually take effect.
 */
export default (
  actionType: string,
  delay: number,
) => (
  _: Store<State>,
) => {
  let timeout: any;
  return (next: Dispatch<AnyAction>) => (action: AnyAction) => {
    if (action.type === actionType) {
      clearTimeout(timeout);
      timeout = setTimeout(() => { next(action); }, delay);
    } else {
      return next(action);
    }
  };
};