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.

Brynne

Memory leak ? Garbage collection! – Iaea

Answer 1

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);

Paramecium

I know this is an old topic but how about setting an array to null? – Orthogenic

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). – Talion

Why do not array = new Array()? – Natika

Answer 2

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);

Iaea

Answer 3

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();

Epizoic

I do want to make it avaible to garbage collection, I want to empty it. – Brynne

Pretty sure arrays in AS3 don't accept strings as keys. Objects do, but not Arrays. – Tetchy

@Omnomlets: you're wrong. next time, try verifying your statements. – Epizoic

You're right. I suppose that's because Array extends Object in the first place. Thanks! You learn something every day. – Tetchy

Answer 4

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());
}

Buggy

Answer 5

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

Oyler