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events: optimize listener array cloning #1050

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events: optimize listener array cloning #1050

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19 changes: 6 additions & 13 deletions lib/events.js
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Original file line number Diff line number Diff line change
Expand Up @@ -384,7 +384,7 @@ EventEmitter.prototype.listeners = function listeners(type) {
else if (typeof evlistener === 'function')
ret = [evlistener];
else
ret = arrayClone(evlistener);
ret = arrayClone(evlistener, evlistener.length);
}

return ret;
Expand Down Expand Up @@ -413,16 +413,9 @@ function spliceOne(list, index) {
list.pop();
}

function arrayClone(arr, len) {
var ret;
if (len === undefined)
len = arr.length;
if (len >= 50)
ret = arr.slice();
else {
ret = new Array(len);
for (var i = 0; i < len; i += 1)
ret[i] = arr[i];
}
return ret;
function arrayClone(arr, i) {
var copy = new Array(i);
while (i--)
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Curious, is iterating backwards faster than forward?

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According to this jsperf and this jsperf it appears so, at least in this case.

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Yeah, it's really micro, but I also always do this when possible/sane, idk I guess I just like the way it looks. XD

copy[i] = arr[i];
return copy;
}