Ilia Mashkov
49 lines
1.4 KiB
TypeScript
49 lines
1.4 KiB
TypeScript
/**
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* Throttles a function to limit execution frequency
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*
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* Ensures a function executes at most once per `wait` milliseconds.
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* Unlike debounce, throttled functions execute on the leading edge
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* and trailing edge if called repeatedly.
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*
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* @example
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* ```ts
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* const logScroll = throttle(() => {
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* console.log('Scroll position:', window.scrollY);
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* }, 100);
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*
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* window.addEventListener('scroll', logScroll);
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* // Will log at most once every 100ms
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* ```
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*
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* @param fn - Function to throttle
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* @param wait - Minimum time between executions in milliseconds
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* @returns Throttled function
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*/
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export function throttle<T extends (...args: any[]) => any>(
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fn: T,
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wait: number,
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): (...args: Parameters<T>) => void {
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let lastCall = 0;
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let timeoutId: ReturnType<typeof setTimeout> | null = null;
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return (...args: Parameters<T>) => {
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const now = Date.now();
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const timeSinceLastCall = now - lastCall;
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if (timeSinceLastCall >= wait) {
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lastCall = now;
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fn(...args);
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} else {
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// Schedule for end of wait period (trailing edge)
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if (timeoutId) {
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clearTimeout(timeoutId);
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}
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timeoutId = setTimeout(() => {
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lastCall = Date.now();
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fn(...args);
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timeoutId = null;
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}, wait - timeSinceLastCall);
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}
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};
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}
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