Small Factorial Code

factorial.js

function factorial( number ){
	return	(
				eval( 
					Object
					.keys( 
						Array(  
							(
									(
										isNaN( parseInt( number ) ) === false
									)
								?	parseInt( number )
								:	NaN
							)
						)
						.join( )
						.split( "," ) 
					)
					.map( ( value ) => parseInt( value ) + 1 )
					.join( "*" ) 
				)
			);
}