I agree with @cbalci and @igandecki. A single loop that iterates the array once is faster than looping the array multiple times.

I agree. This is not a best practice. The instance should be protected from direct modification by declaring it as a variable inside a closure.

Comparing 'for loop' to 'indexOf' is not the correct analysis here. The above solution goes throught the remaining list every time it removes an item. @Igandecki's point is fair. A single pass solution can be more efficent than this one.

Very interesting, I have no idea how this could possibly be true.. I will have to investigate. :)

Thanks!

Since isn't really a closure, there is public access to change Singleton.__instance. Is this really best practice?

@Igandecki

Time complexity is bounded by indexOf and splice which is the fastest way since we dont have to iterate through the array completely. Strangly even doing indexOf multiple times is faster than interating through the array completely. So it's the best way to do it.

source: http://jsperf.com/js-for-loop-vs-array-indexof/8