JavaScript Quirks

A list of JavaScript quirks which should be kept in mind when writing implementations.

Rounding

The JavaScript standard (ECMA-262) defines the behavior of Math.round such that "ties" (e.g., 1.5 and -1.5) are rounded toward +infinity.
```
var x = Math.round( 1.5 );
// returns 2.0

x = Math.round( -1.5 );
// returns -1.0
```
This behavior is relatively uncommon among languages implementing a round operation for floating-point numbers and appears to have originated by following Java.

When implementing lower-level math functions which may require rounding, exercise caution when considering whether the built-in rounding behavior is appropriate and ensure that bias is not introduced in computed results.