@naturalcycles/js-lib/dist/decorators/debounce.js

Standard library for universal (browser + Node.js) javascript

export function _debounce(func, wait, opt = {}) {
    let lastArgs;
    let lastThis;
    let result;
    let timerId;
    let lastCallTime;
    let lastInvokeTime = 0;
    const maxing = 'maxWait' in opt;
    const { leading = false, trailing = true } = opt;
    const maxWait = maxing ? Math.max(Number(opt.maxWait) || 0, wait) : opt.maxWait;
    function invokeFunc(time) {
        const args = lastArgs;
        const thisArg = lastThis;
        lastArgs = lastThis = undefined;
        lastInvokeTime = time;
        result = func.apply(thisArg, args);
        return result;
    }
    function startTimer(pendingFunc, wait) {
        return setTimeout(pendingFunc, wait);
    }
    function cancelTimer(id) {
        clearTimeout(id);
    }
    function leadingEdge(time) {
        // Reset any `maxWait` timer.
        lastInvokeTime = time;
        // Start the timer for the trailing edge.
        timerId = startTimer(timerExpired, wait);
        // Invoke the leading edge.
        return leading ? invokeFunc(time) : result;
    }
    function remainingWait(time) {
        const timeSinceLastCall = time - lastCallTime;
        const timeSinceLastInvoke = time - lastInvokeTime;
        const timeWaiting = wait - timeSinceLastCall;
        return maxing ? Math.min(timeWaiting, maxWait - timeSinceLastInvoke) : timeWaiting;
    }
    function shouldInvoke(time) {
        const timeSinceLastCall = time - lastCallTime;
        const timeSinceLastInvoke = time - lastInvokeTime;
        // Either this is the first call, activity has stopped and we're at the
        // trailing edge, the system time has gone backwards and we're treating
        // it as the trailing edge, or we've hit the `maxWait` limit.
        return (lastCallTime === undefined ||
            timeSinceLastCall >= wait ||
            timeSinceLastCall < 0 ||
            (maxing && timeSinceLastInvoke >= maxWait));
    }
    function timerExpired() {
        const time = Date.now();
        if (shouldInvoke(time)) {
            return trailingEdge(time);
        }
        // Restart the timer.
        timerId = startTimer(timerExpired, remainingWait(time));
    }
    function trailingEdge(time) {
        timerId = undefined;
        // Only invoke if we have `lastArgs` which means `func` has been
        // debounced at least once.
        if (trailing && lastArgs) {
            return invokeFunc(time);
        }
        lastArgs = lastThis = undefined;
        return result;
    }
    function cancel() {
        if (timerId !== undefined) {
            cancelTimer(timerId);
        }
        lastInvokeTime = 0;
        lastArgs = lastCallTime = lastThis = timerId = undefined;
    }
    function flush() {
        return timerId === undefined ? result : trailingEdge(Date.now());
    }
    function pending() {
        return timerId !== undefined;
    }
    function debounced(...args) {
        const time = Date.now();
        const isInvoking = shouldInvoke(time);
        lastArgs = args;
        lastThis = this;
        lastCallTime = time;
        if (isInvoking) {
            if (timerId === undefined) {
                return leadingEdge(lastCallTime);
            }
            if (maxing) {
                // Handle invocations in a tight loop.
                timerId = startTimer(timerExpired, wait);
                return invokeFunc(lastCallTime);
            }
        }
        if (timerId === undefined) {
            timerId = startTimer(timerExpired, wait);
        }
        return result;
    }
    debounced.cancel = cancel;
    debounced.flush = flush;
    debounced.pending = pending;
    return debounced;
}
export function _throttle(func, wait, opt = {}) {
    return _debounce(func, wait, {
        leading: true,
        trailing: true,
        ...opt,
        maxWait: wait,
    });
}