ix/asynciterable/operators/debounce.js

The Interactive Extensions for JavaScript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.debounce = exports.DebounceAsyncIterable = void 0;
const tslib_1 = require("tslib");
const asynciterablex_js_1 = require("../asynciterablex.js");
const aborterror_js_1 = require("../../aborterror.js");
/** @ignore */
class DebounceAsyncIterable extends asynciterablex_js_1.AsyncIterableX {
    constructor(source, time) {
        super();
        this._source = source;
        this._time = time;
    }
    [Symbol.asyncIterator](signal) {
        return tslib_1.__asyncGenerator(this, arguments, function* _a() {
            (0, aborterror_js_1.throwIfAborted)(signal);
            let done = false;
            let reject = () => {
                /**/
            };
            let resolve = () => {
                /**/
            };
            let promise = new Promise((r1, r2) => {
                resolve = r1;
                reject = r2;
            });
            (() => tslib_1.__awaiter(this, void 0, void 0, function* () {
                let id = null;
                const emitValue = (value) => {
                    id = null;
                    resolve(value);
                    promise = new Promise((r1, r2) => {
                        resolve = r1;
                        reject = r2;
                    });
                };
                if (signal) {
                    signal.addEventListener('abort', () => {
                        done = true;
                        if (id) {
                            clearTimeout(id);
                        }
                        id = null;
                        reject(new aborterror_js_1.AbortError());
                    }, { once: true });
                }
                try {
                    let result;
                    // @ts-ignore
                    const it = this._source[Symbol.asyncIterator](signal);
                    // 1. check `!done`
                    // 2. await next value
                    // 3. check `!done` again, in case the signal aborted while the promise was pending
                    while (!done && !(result = yield it.next()).done && !done) {
                        if (id) {
                            clearTimeout(id);
                        }
                        id = setTimeout(emitValue, this._time, result.value);
                    }
                }
                catch (e) {
                    reject(e);
                }
                done = true;
            }))();
            while (!done) {
                yield yield tslib_1.__await(yield tslib_1.__await(promise));
            }
        });
    }
}
exports.DebounceAsyncIterable = DebounceAsyncIterable;
/**
 * Emits a notification from the source async-iterable only after a particular time span
 * has passed without another source emission.
 *
 * @template TSource The type of elements in the source sequence.
 * @param {number} time The timeout duration in milliseconds
 * @returns {MonoTypeOperatorAsyncFunction<TSource>} An operator function which debounces by the given timeout.
 */
function debounce(time) {
    return function debounceOperatorFunction(source) {
        return new DebounceAsyncIterable(source, time);
    };
}
exports.debounce = debounce;

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