eewing
83 lines
2.5 KiB
JavaScript
83 lines
2.5 KiB
JavaScript
import { untrack } from "svelte";
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export function useThrottle(callback, interval = 250) {
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let lastCall = 0;
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let timeout = $state();
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let resolve = null;
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let reject = null;
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let promise = null;
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function reset() {
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timeout = undefined;
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promise = null;
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resolve = null;
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reject = null;
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}
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function throttled(...args) {
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return untrack(() => {
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const now = Date.now();
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const intervalValue = typeof interval === "function" ? interval() : interval;
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const nextAllowedTime = lastCall + intervalValue;
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if (!promise) {
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promise = new Promise((res, rej) => {
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resolve = res;
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reject = rej;
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});
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}
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if (now < nextAllowedTime) {
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if (!timeout) {
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timeout = setTimeout(async () => {
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try {
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const result = await callback.apply(this, args);
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resolve?.(result);
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}
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catch (error) {
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reject?.(error);
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}
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finally {
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clearTimeout(timeout);
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reset();
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lastCall = Date.now();
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}
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}, nextAllowedTime - now);
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}
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return promise;
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}
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if (timeout) {
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clearTimeout(timeout);
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timeout = undefined;
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}
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lastCall = now;
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try {
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const result = callback.apply(this, args);
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resolve?.(result);
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}
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catch (error) {
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reject?.(error);
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}
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finally {
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reset();
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}
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return promise;
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});
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}
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throttled.cancel = async () => {
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if (timeout) {
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if (timeout === undefined) {
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// Wait one event loop to see if something triggered the throttled function
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await new Promise((resolve) => setTimeout(resolve, 0));
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if (timeout === undefined)
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return;
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}
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clearTimeout(timeout);
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reject?.("Cancelled");
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reset();
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}
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};
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Object.defineProperty(throttled, "pending", {
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enumerable: true,
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get() {
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return !!timeout;
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},
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});
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return throttled;
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}
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