Why does Java 8 Nashorn (JavaScript) modulo returns 0.0 (double) instead of 0 (integer)? -

consider following code sample:

import javax.script.scriptengine; import javax.script.scriptenginemanager;  public class tester {    public static void main( string[] args ) throws exception {       scriptengine se = new scriptenginemanager().getenginebyname( "nashorn" );        object eval = se.eval( "5%5" );        system.out.println( "eval = " + eval );       system.out.println( "eval.getclass() = " + eval.getclass() );   } } 

why produces following output?

eval = 0.0
eval.getclass() = class java.lang.double

the result type java.lang.double weird.

in case remainder different 0 correctly returns java.lang.integer, e.g. 5%2 returns java.lang.integer' value1`.

only 0 somehow special.

trying same javascript expression in firefox 32.0.2 (findbugs console) works fine , returns plain 0.

is there way force nashorn return integer type instead of double?

there no integers in javascript.

start ecmascript section 8: types:

the ecmascript language types undefined, null, boolean, string, number, , object.

then see ecmascript section 8.5: number type:

the number type has 18437736874454810627 (that is, 264−253+3) values, representing double-precision 64-bit format ieee 754 values ..." (emphasis added)

the fact firefox displays floating point value 1 "1" rather "1.0" irrelevant, , confusing you.