Strange behaviour with JS; Can someone explain this output?

Question

I'm studying Node.js and recently found that bit OR operator(|) can cause strange behaviour.

~~~~~~~~~~
> 9 | 0
9
> 99 | 0
99
...
> 999999999 | 0
999999999
> 9999999999 | 0
1410065407
> 99999999999 | 0
1215752191
~~~~~~~~~~

(tested on Node.js v12.18.2)

Can someone explain this behaviour?

P.S. Now I noticed that with many more digits the output is always zero.

~~~~~~~~~~
> 9999999999999999999999999 | 0
-2147483648
> 99999999999999999999999999 | 0
0
> 999999999999999999999999999 | 0
0
> 9999999999999999999999999999 | 0
0
~~~~~~~~~~

Why? I'm confused by this. What is the exact behaviour of bit OR operator in Node.js?

Answer 1

when working with bitwise/shift operators in javascript, 32bit signed integers are used, so the largest safe number you can use is 2^(31)-1 or 2147483647.
Otherwise it overflows.