Created
January 15, 2018 01:18
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/** | |
* 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 | |
*/ | |
module.exports = 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; | |
}; |
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