[LambdaTrain]

To deal with overflow the size of variable a needs to be doubled. This trick, if applied correctly, uses the same amounts of memory.

Now you may wonder whether we can mathematically prove swapping two variavles requires memory of three variables in digital computer...

[joe_the_user]

You could use unsigned ints, whose arithmetic wraps, to deal with the overflow.

I'd still be curious about any theories of storage.

[charcircuit]

Javacript doesn't have an unsigned int datatype. The numbers in the article were doubles.

[nayuki]

No - to deal with overflow, the variables need to be widened by 1 bit.

[prophesi]

Not sure if this is what the OP meant, but adding a bit is effectively doubling the size. 16 bits = 65535. 17 = 131071.

[LambdaTrain]

the second half my comment is wrong. As someone comment points out there is xor swap