70 lines
1.5 KiB
TypeScript
70 lines
1.5 KiB
TypeScript
// Copyright 2023 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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// eslint-disable-next-line @typescript-eslint/ban-types
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export function throttle(func: Function, wait: number): () => void {
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let lastCallTime: number;
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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let lastArgs: Array<any> | undefined;
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let timerId: NodeJS.Timeout | undefined;
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function call() {
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const args = lastArgs || [];
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lastArgs = undefined;
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func(...args);
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}
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function leading() {
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timerId = setTimeout(timerExpired, wait);
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call();
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}
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function remainingWait(time: number) {
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const timeSinceLastCall = time - lastCallTime;
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return wait - timeSinceLastCall;
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}
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function shouldInvoke(time: number) {
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const timeSinceLastCall = time - lastCallTime;
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return (
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lastCallTime === undefined ||
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timeSinceLastCall >= wait ||
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timeSinceLastCall < 0
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);
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}
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function timerExpired() {
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const time = Date.now();
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if (shouldInvoke(time)) {
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return trailing();
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}
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timerId = setTimeout(timerExpired, remainingWait(time));
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}
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function trailing() {
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timerId = undefined;
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if (lastArgs) {
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return call();
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}
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lastArgs = undefined;
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}
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return (...args) => {
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const time = Date.now();
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const isInvoking = shouldInvoke(time);
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lastArgs = args;
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lastCallTime = time;
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if (isInvoking) {
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if (timerId === undefined) {
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return leading();
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}
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}
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if (timerId === undefined) {
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timerId = setTimeout(timerExpired, wait);
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}
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};
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}
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