negativeZero.js - tiny JavaScript function to differentiate -0 from +0 (can process any type other than Symbol or BigInt)

negativeZero.js

// negativeZero.js - tiny JavaScript function to differentiate -0 from +0 (can process any type other than Symbol or BigInt)

// 15 chars:	N=a=>1/0==1/-a;
var negativeZero = v => Infinity === 1 / -v;	// => v === 0 && Number.NEGATIVE_INFINITY === 1 / v;



var isWeb = Date.now;	// JScript is missing this method

var values = [

	 -0,
	"-0",
	 -0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,
	"-0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001",

	 -0.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001,
	"-0.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001",
	0,
	"0",
	-Infinity,
	"-Infinity",
	Infinity,
	"Infinity",
	-1,
	"-1",
	1,
	"1",
	-7,
	"-7",
	7,
	"7",

	NaN,
	"Z",
	"",
	[-0],
	{},
	new Date(),
	Date,
	/foo/img,
	false,
	true,
	null,
	void 0

].concat(

	isWeb ? [
		new BigUint64Array(),
		new Int8Array(),
		new Map(),
		new Set(),
		eval("()=>{}"),
		eval("( () => function*() {} )()"),
		eval("new Promise(()=>{})"),
		// Symbol(),	// TypeError: Cannot convert a Symbol value to a number
		// BigInt(-0),	// TypeError: Cannot convert a BigInt value to a number
		// BigInt(0),
		// BigInt(-Infinity),
		// BigInt(Infinity),
		// BigInt(-1),
		// BigInt(1),
		// BigInt(-7),
		// BigInt(7),
	]

	: []

);



if(isWeb) {

	eval("values.forEach( v => console.log( negativeZero(v) ) );");

} else {	// JScript-compatible...

	// 32 chars:	N=function(a){return 1/0==1/-a};
	var negativeZero_JScript = function(v) {
		return Infinity === 1 / -v;	// return v === 0 && Number.NEGATIVE_INFINITY === 1 / v;
	};

	console = { log: function() { var a = arguments; if(a.length) WScript.Echo( [].join.call(a, " ") ); } };
	for(var i in values) console.log( negativeZero_JScript(values[i]) );

};

// (4) true
// (35) false (28 in JScript)



// NOTE: "If all else fails, add zero."
// https://stackoverflow.com/questions/7223359/are-0-and-0-the-same/53135516#53135516
console.log([
	negativeZero( Math.round(-0.0001) ),	// true
	negativeZero( Math.trunc(-0.0001) ),	// true
	negativeZero( Math.ceil(-0.0001)  ),	// true

	negativeZero( Math.ceil(-0.0001) +0  ),	// false
	negativeZero( Math.round(-0.0001) +0 ),	// false
	negativeZero( Math.ceil(-0.0001) +0  ),	// false
]);