I do not understand about bitwise operator in Javascript

I am student studying programming.

As far as I know, Javascript saves number as float.

However, bitwise operator in Javascript run as a type of number is integer.

For instance,

> 1 | 2 // -> 3
> 2 << 4 // -> 32

How is it possible?

I find official documentation(mdn web docs), but I can not find the reason.