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45 lines
861 B
45 lines
861 B
4 weeks ago
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/**
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* Throttle decorator
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* @param {Function} fn
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* @param {Number} freq
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* @return {Function}
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*/
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function throttle(fn, freq) {
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let timestamp = 0;
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let threshold = 1000 / freq;
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let lastArgs;
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let timer;
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const invoke = (args, now = Date.now()) => {
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timestamp = now;
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lastArgs = null;
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if (timer) {
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clearTimeout(timer);
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timer = null;
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}
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fn.apply(null, args);
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}
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const throttled = (...args) => {
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const now = Date.now();
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const passed = now - timestamp;
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if ( passed >= threshold) {
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invoke(args, now);
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} else {
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lastArgs = args;
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if (!timer) {
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timer = setTimeout(() => {
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timer = null;
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invoke(lastArgs)
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}, threshold - passed);
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}
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}
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}
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const flush = () => lastArgs && invoke(lastArgs);
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return [throttled, flush];
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}
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export default throttle;
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