52 lines
1.1 KiB
JavaScript
52 lines
1.1 KiB
JavaScript
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//@ts-check
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/**
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*
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* Creates a throttled function that only invokes the provided function at most
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* once per within a given number of milliseconds.
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*
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* @template {(...args: any) => any } F
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* @template {ReturnType<F>} R
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* @template {Parameters<F>} P
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* @param {F} func
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* @param {number} [firingRateMs] Firing rate (50ms by default)
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*/
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export const throttle = (func, firingRateMs = 50) => {
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/** @type {R} */
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let lastResult;
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/** @type {number} */
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let last = 0;
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/** @type {null|P} */
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let funcArguments;
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/** @type {number} */
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let timeoutID = 0;
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const call = () => {
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timeoutID = 0;
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last = +new Date();
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lastResult = func.apply(null, funcArguments);
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funcArguments = null;
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};
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/***
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* @param {P} args
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*/
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const throttled = (...args) => {
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funcArguments = args;
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const delta = new Date().getTime() - last;
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if (!timeoutID)
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if (delta >= firingRateMs) {
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call();
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} else {
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timeoutID = setTimeout(call, firingRateMs - delta);
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}
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return lastResult;
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};
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return throttled;
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};
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export default throttle
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