thi-ng/umbrella

import type { MaybeAsyncIterable } from "@thi.ng/api";
import type { AsyncTransducer } from "./api.js";
import { iterator1 } from "./iterator.js";
import { throttle } from "./throttle.js";

export function throttleTime<T>(delay: number): AsyncTransducer<T, T>;
export function throttleTime<T>(
    delay: number,
    src: MaybeAsyncIterable<T>
): AsyncIterableIterator<T>;
export function throttleTime<T>(delay: number, src?: MaybeAsyncIterable<T>) {
    return src
        ? iterator1(throttleTime(delay), src)
        : throttle(() => {
                let last = 0;
                return () => {
                    const t = Date.now();
                    return t - last >= delay ? ((last = t), true) : false;
                };
          });
}