[thelist] [JS] Modulo Operator question

[Kasimir K]

As JavaScript seems a bit vague with this - reference says int, but you 
do in practice get float - I had a look at what ecma 262 says (sorry, 
only found it as pdf, so I paste some here):

"
11.5.3 Applying the % Operator
The % operator yields the remainder of its operands from an implied 
division; the left operand is the dividend and the right operand is the 
divisor.

NOTE
In C and C++, the remainder operator accepts only integral operands; in 
ECMAScript, it also accepts floating-point operands.

The result of a floating-point remainder operation as computed by the % 
operator is not the same as the “remainder” operation defined by IEEE 
754. The IEEE 754 “remainder” operation computes the remainder from a 
rounding division, not a truncating division, and so its behaviour is 
not analogous to that of the usual integer remainder operator. Instead 
the ECMAScript language defines % on floatingpoint operations to behave 
in a manner analogous to that of the Java integer remainder operator; 
this may be compared with the C library function fmod.

The result of a ECMAScript floating-point remainder operation is 
determined by the rules of IEEE arithmetic:
• If either operand is NaN, the result is NaN.
• The sign of the result equals the sign of the dividend.
• If the dividend is an infinity, or the divisor is a zero, or both, the 
result is NaN.
• If the dividend is finite and the divisor is an infinity, the result 
equals the dividend.
• If the dividend is a zero and the divisor is finite, the result is the 
same as the dividend.
• In the remaining cases, where neither an infinity, nor a zero, nor NaN 
is involved, the floating-point remainder r from a dividend n and a 
divisor d is defined by the mathematical relation r = n - (d * q) where 
q is an integer that is negative only if n/d is negative and positive 
only if n/d is positive, and whose magnitude is as large as possible 
without exceeding the magnitude of the true mathematical quotient of n 
and d.
"

According to this it is pretty clear: if dividend or divisor is float, 
the mod is flot too.

.k