/**
* Copyright (c) 2000-present Liferay, Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by the Free
* Software Foundation; either version 2.1 of the License, or (at your option)
* any later version.
*
* This library is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
* details.
*/
/**
* Throttle implementation that fires on the leading and trailing edges.
* If multiple calls come in during the throttle interval, the last call's
* arguments and context are used, replacing those of any previously pending
* calls.
*
* @param {!function()} fn
* @param {number} interval
* @return {!function()}
*/
export default function throttle(fn, interval) {
let timeout = null;
let last;
return function (...args) {
const context = this;
const now = Date.now();
const schedule = () => {
timeout = setTimeout(() => {
timeout = null;
}, interval);
last = now;
fn.apply(context, args);
};
if (timeout === null) {
schedule();
}
else {
const remaining = Math.max(last + interval - now, 0);
clearTimeout(timeout);
timeout = setTimeout(schedule, remaining);
}
};
}