You're describing array of structs vs. struct of arrays. Even in JavaScript, you would have to manually do the latter.

V8 automatically optimizes objects with the same shape into efficient structs, making array of objects much more efficient than in Java.

And the manually manager int array acts more like system memory, it's not continuous, so you could have point i 0 and 2 and the data would be: [1, 2, 3, x, x,x, 3, 2, 1] (3D points).

So I am not describing a struct of arrays.

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spankalee an hour ago | parent [-]

Hidden class optimizations just make JavaScript objects behave a little more like Java class instances, where the VM knows where to find each field, rather than having to look it up like a map.

It doesn't make JS faster than Java, it makes it almost as fast in some cases.

	▲	kykat 5 minutes ago \| parent [-]
		I can only say what I observed in testing, and that's that having millions of instances of a class like Point3D{x, y, z} in JS uses significantly less memory than in Java (this was tested on Android, not sure if relevant). It was quite some time ago so I don't remember the details.