1.4.7 Unary - Operator

UnaryExpression : - UnaryExpression

function evaluate(- UnaryExpression) {
var expr = UnaryExpression;
var oldValue = ToNumber(GetValue(UnaryExpression));
if (isNaN(oldValue)) return NaN;
return -oldValue; // it's cheating, I know :)
}


Note that +0 becomes -0 and vice versa. NaN just returns NaN.