JavaScript numbers can hold integers without losing precision up to Number.MAX_SAFE_INTEGER (9007199254740991, or 2⁵³-1), can be checked with Number.isSafeInteg

JavaScript numbers can hold integers without losing precision up to Number.MAX_SAFE_INTEGER (9007199254740991, or 2⁵³-1), can be checked with Number.isSafeInteger(). Bitwise arithmetics, though, works on 32-bit numbers, so "casting" with | 0 will actually result in converting the number to 32-bit signed integer: 2**53-1 | 0 = -1 2**53-2 | 0 = -2 Which is modular arithmetic: (2**53-2) % 2**32 = 4294967294 2**53-2 >>> 0 = 4294967294 ( >>> 0 makes unsigned, 4294967294 | 0 = -2)