JavaScript integer shift safety: (n << 1) != (n * 2)

Question

Digging JS just discovered something new to me:

n = 0xffffffff
4294967295
n
4294967295
n << 1
-2
n * 2
8589934590
(n << 1) == (n * 2)
false
n + 1
4294967296

This is console output of builtin FireFox (51.0.1 64-bit) debugger...

What I have read so far (w3school, etc), does not allow me to suspect such a behaviour.

Is it ok or have I something missed?

...To be continued...

Answer 1

n << b handles n and the result as int 32, whereas n * 2 handles n and the 2 as number.

Note that 4294967295 << 0 will be -1.