audiobookshelf/server/libs/watcher/debounce.js

71 lines
1.8 KiB
JavaScript

/**
* Returns a function, that, as long as it continues to be invoked, will not
* be triggered. The function will be called after it stops being called for
* N milliseconds. If `immediate` is passed, trigger the function on the
* leading edge, instead of the trailing. The function also has a property 'clear'
* that is a function which will clear the timer to prevent previously scheduled executions.
*
* @source underscore.js
* @see http://unscriptable.com/2009/03/20/debouncing-javascript-methods/
* @param {Function} function to wrap
* @param {Number} timeout in ms (`100`)
* @param {Boolean} whether to execute at the beginning (`false`)
* @api public
*/
function debounce(func, wait, immediate) {
var timeout, args, context, timestamp, result;
if (null == wait) wait = 100;
function later() {
var last = Date.now() - timestamp;
if (last < wait && last >= 0) {
timeout = setTimeout(later, wait - last);
} else {
timeout = null;
if (!immediate) {
result = func.apply(context, args);
context = args = null;
}
}
};
var debounced = function () {
context = this;
args = arguments;
timestamp = Date.now();
var callNow = immediate && !timeout;
if (!timeout) timeout = setTimeout(later, wait);
if (callNow) {
result = func.apply(context, args);
context = args = null;
}
return result;
};
debounced.clear = function () {
if (timeout) {
clearTimeout(timeout);
timeout = null;
}
};
debounced.flush = function () {
if (timeout) {
result = func.apply(context, args);
context = args = null;
clearTimeout(timeout);
timeout = null;
}
};
return debounced;
};
// Adds compatibility for ES modules
debounce.debounce = debounce;
module.exports = debounce;