49 lines
1.5 KiB
JavaScript
49 lines
1.5 KiB
JavaScript
/**
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* @file
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* Adapted from underscore.js with the addition Drupal namespace.
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*/
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/**
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* Limits the invocations of a function in a given time frame.
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*
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* The debounce function wrapper should be used sparingly. One clear use case
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* is limiting the invocation of a callback attached to the window resize event.
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*
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* Before using the debounce function wrapper, consider first whether the
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* callback could be attached to an event that fires less frequently or if the
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* function can be written in such a way that it is only invoked under specific
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* conditions.
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*
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* @param {function} func
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* The function to be invoked.
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* @param {number} wait
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* The time period within which the callback function should only be
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* invoked once. For example if the wait period is 250ms, then the callback
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* will only be called at most 4 times per second.
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* @param {bool} immediate
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* Whether we wait at the beginning or end to execute the function.
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*
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* @return {function}
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* The debounced function.
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*/
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Drupal.debounce = function (func, wait, immediate) {
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let timeout;
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let result;
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return function (...args) {
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const context = this;
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const later = function () {
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timeout = null;
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if (!immediate) {
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result = func.apply(context, args);
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}
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};
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const callNow = immediate && !timeout;
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clearTimeout(timeout);
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timeout = setTimeout(later, wait);
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if (callNow) {
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result = func.apply(context, args);
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}
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return result;
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};
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};
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