define(['./now'], function (now) {
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// Returns a function, that, when invoked, will only be triggered at most once
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// during a given window of time. Normally, the throttled function will run
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// as much as it can, without ever going more than once per `wait` duration;
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// but if you'd like to disable the execution on the leading edge, pass
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// `{leading: false}`. To disable execution on the trailing edge, ditto.
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function throttle(func, wait, options) {
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var timeout, context, args, result;
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var previous = 0;
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if (!options) options = {};
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var later = function() {
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previous = options.leading === false ? 0 : now();
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timeout = null;
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result = func.apply(context, args);
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if (!timeout) context = args = null;
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};
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var throttled = function() {
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var _now = now();
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if (!previous && options.leading === false) previous = _now;
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var remaining = wait - (_now - previous);
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context = this;
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args = arguments;
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if (remaining <= 0 || remaining > wait) {
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if (timeout) {
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clearTimeout(timeout);
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timeout = null;
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}
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previous = _now;
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result = func.apply(context, args);
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if (!timeout) context = args = null;
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} else if (!timeout && options.trailing !== false) {
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timeout = setTimeout(later, remaining);
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}
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return result;
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};
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throttled.cancel = function() {
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clearTimeout(timeout);
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previous = 0;
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timeout = context = args = null;
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};
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return throttled;
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}
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return throttle;
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});
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