92 lines
2.7 KiB
JavaScript
92 lines
2.7 KiB
JavaScript
/* IMPORT */
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/* MAIN */
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const debounce = (fn, wait = 1, options) => {
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/* VARIABLES */
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wait = Math.max(1, wait);
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const leading = options?.leading ?? false;
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const trailing = options?.trailing ?? true;
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const maxWait = Math.max(options?.maxWait ?? Infinity, wait);
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let args;
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let timeout;
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let timestampCall = 0;
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let timestampInvoke = 0;
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/* HELPERS */
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const getInstantData = () => {
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const timestamp = Date.now();
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const elapsedCall = timestamp - timestampCall;
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const elapsedInvoke = timestamp - timestampInvoke;
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const isInvoke = (elapsedCall >= wait || elapsedInvoke >= maxWait);
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return [timestamp, isInvoke];
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};
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const invoke = (timestamp) => {
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timestampInvoke = timestamp;
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if (!args)
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return; // This should never happen
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const _args = args;
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args = undefined;
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fn.apply(undefined, _args);
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};
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const onCancel = () => {
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resetTimeout(0);
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};
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const onFlush = () => {
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if (!timeout)
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return;
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onCancel();
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invoke(Date.now());
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};
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const onLeading = (timestamp) => {
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timestampInvoke = timestamp;
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if (leading)
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return invoke(timestamp);
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};
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const onTrailing = (timestamp) => {
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if (trailing && args)
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return invoke(timestamp);
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args = undefined;
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};
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const onTimeout = () => {
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timeout = undefined;
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const [timestamp, isInvoking] = getInstantData();
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if (isInvoking)
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return onTrailing(timestamp);
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return updateTimeout(timestamp);
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};
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const updateTimeout = (timestamp) => {
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const elapsedCall = timestamp - timestampCall;
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const elapsedInvoke = timestamp - timestampInvoke;
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const remainingCall = wait - elapsedCall;
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const remainingInvoke = maxWait - elapsedInvoke;
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const ms = Math.min(remainingCall, remainingInvoke);
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return resetTimeout(ms);
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};
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const resetTimeout = (ms) => {
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if (timeout)
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clearTimeout(timeout);
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if (ms <= 0)
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return;
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timeout = setTimeout(onTimeout, ms);
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};
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/* DEBOUNCED */
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const debounced = (...argsLatest) => {
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const [timestamp, isInvoking] = getInstantData();
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const hadTimeout = !!timeout;
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args = argsLatest;
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timestampCall = timestamp;
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if (isInvoking || !timeout)
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resetTimeout(wait);
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if (isInvoking) {
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if (!hadTimeout)
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return onLeading(timestamp);
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return invoke(timestamp);
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}
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};
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/* DEBOUNCED UTILITIES */
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debounced.cancel = onCancel;
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debounced.flush = onFlush;
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/* RETURN */
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return debounced;
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};
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/* EXPORT */
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export default debounce;
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