As3 - How to clear an array efficiently?

Question

I've been looking to clear an array in ActionScript 3.

Some method suggest : array = []; (Memory leak?)

Other would say : array.splice(0);

If you have any other, please share. Which one is the more efficient?

Thank you.

Memory leak ? Garbage collection! – n4pgamer Oct 03 '13 at 19:11 — n4pgamer, Oct 03 '13 at 19:11

score 29 · Accepted Answer · answered Feb 10 '10 at 15:04

29

array.length = 0 or array.splice() seems to work best for overall performance.

array.splice(0); will perform faster than array.splice(array.length - 1, 1);

answered Feb 10 '10 at 15:04

Jason

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I know this is an old topic but how about setting an array to null? – drpelz Feb 27 '12 at 22:07
5

Actually `array = null;` gets rid of the Array itself instead of just cleaning it. Its basically the same that happens when you `array = [];`, the previous array reference is lost and will probably be garbage collected (which might not be the wanted outcome). – Biro456 Dec 21 '12 at 19:48
1

Why do not `array = new Array()`? – Gaston Flores Jul 19 '13 at 15:43

score 6 · Answer 2 · answered Feb 27 '13 at 11:16

6

For array with 100 elements (benchmarks in ms, the lower the less time needed):

// best performance (benchmark: 1157)
array.length = 0;
// lower performance (benchmark: 1554)
array = [];
// even lower performance (benchmark: 3592)
array.splice(0);

answered Feb 27 '13 at 11:16

n4pgamer

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score 2 · Answer 3 · answered Jun 06 '12 at 23:33

There is a key difference between array.pop() and array.splice(array.length - 1, 1) which is that pop will return the value of the element. This is great for handy one liners when clearing out an array like:

while(myArray.length > 0){
     view.removeChild(myArray.pop());
}

score 2 · Answer 4 · edited Jul 19 '13 at 15:26

2

I wonder, why you want to clear the Array in that manner? clearing all references to that very array will make it available for garbage collection. array = [] will do so, if array is the only reference to the array. if it isn't then you maybe shouldn't be emtpying it (?)

also, please note that`Arrays accept Strings as keys. both splice and lenght operate solely on integer keys, so they will have no effect on String keys.

btw.: array.splice(array.length - 1, 1); is equivalent to array.pop();

edited Jul 19 '13 at 15:26

Taryn

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answered Feb 10 '10 at 16:35

back2dos

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I do want to make it avaible to garbage collection, I want to empty it. – ALOToverflow Feb 10 '10 at 18:28
Pretty sure arrays in AS3 don't accept strings as keys. Objects do, but not Arrays. – Austin Fitzpatrick Feb 10 '10 at 18:30
@Omnomlets: you're wrong. next time, try verifying your statements. – back2dos Feb 10 '10 at 18:44
You're right. I suppose that's because Array extends Object in the first place. Thanks! You learn something every day. – Austin Fitzpatrick Feb 10 '10 at 18:54

score 1 · Answer 5 · edited May 03 '12 at 14:23

1

array.splice(0,array.length);

this has always worked pretty well for me but I haven't had a chance to run it through the profiler yet

edited May 03 '12 at 14:23

Sergey Glotov

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answered May 03 '12 at 14:18

chris

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As3 - How to clear an array efficiently?

5 Answers5