Flooring numbers in JavaScript: ~~n, n|0 or Math.floor(n)?

Question

I've recently discovered some other ways to remove the fractional part of numeric values in JavaScript other than Math.floor(n), specifically the double bitwise NOT operator ~~n and performing a bitwise or with 0 n|0.

I'd like to know what are the difference between these approaches and what the different scenarios are where one method is recommended over another.

Answer 1

The operands of all bitwise operators are converted to signed 32-bit integers:

Math.floor(2147483648) // 2147483648
2147483648 | 0         // 2147483648
~~2147483648           // 2147483648

Math.floor(2147483649) // 2147483649
2147483649 | 0         // -2147483647
~~2147483649           // -2147483647

So use Math.floor();

Answer 2

Be clear to the next person looking at your code and use Math.floor().

The performance gain of 1%-40% isn't really worth it, so don't make your code confusing and hard to maintain.