mdev - 10 months ago 51

Javascript Question

`var lst = [/*List of items*/];`

for (var i = 10; i > 0; i--) {

lst.appendChild(lst[Math.random() * i | 0]);

}

Why would "|" be in a index? Does this function shuffle the list 'lst'?

Answer

The bitwise OR operator | converts its input to a 32-bit two-complement number. This is often used for fast rounding towards zero (faster than Math.trunc()).

```
console.log(1.1 | 0); // 1
console.log(1.9 | 0); // 1
console.log(-1.1 | 0); // -1
console.log(-1.9 | 0); // -1
```

PS: A double bitwise negation ~~ has the same effect. Keep in mind that applying bitwise operators effectively reduces the range of integer operands from Number.MAX_SAFE_INTEGER (2⁵³ - 1) to the maximum 32-bit two-complement (2³¹ - 1).