Question

I’m improving the performance of a HTML5 Game,while I reset some arrays,in order to reduce the garbage collection,I tend to use array.length=0(Yet I’m not sure if it’s working in real world)
I did some tests to find out the speed of these 2 types of reset array here
http://tinkerbin.com/hqQvp5fQ

Answer 1

Yes, setting length to zero is a better solution since it truncates an existing array while arr=[] creates a new array and stores a reference to it in arr. It may happen that the old array isn’t referenced any more and will be garbage collected. Hence, arr=[] may require an extra allocation and garbage collection compared to arr.length=0.

See this for the description of the special behavior of the length property on which this relies.