b2whats/index.html

## index.html
<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8"/>
	<title>(key in object) vs. (object[key] !== void 0) vs. object.hasOwnProperty(key)</title>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/benchmark/1.0.0/benchmark.min.js"></script>
	<script src="./suite.js"></script>
</head>
<body>
	<h1>Open the console to view the results</h1>
	<h2><code>cmd + alt + j</code> or <code>ctrl + alt + j</code></h2>
</body>
</html>

## suite.js
"use strict";

(function (factory) {
	if (typeof Benchmark !== "undefined") {
		factory(Benchmark);
	} else {
		factory(require("benchmark"));
	}
})(function (Benchmark) {
	var suite = new Benchmark.Suite;

	Benchmark.prototype.setup = function () {
		var object = {};
		for (var i = 0; i < 5; i++) {
		   object[i + '_' + Math.random()] = Math.random();
		}
	};


	suite.add("in", function () {
		/** in **/
		var results = [];
		for (var i = 0; i < 10; i++) {
		    var key = '_' + Math.random() + i;
		    (key in object) && results.push(key);
		}
		if (results.length) throw 'wtf?';
	});

	suite.add("void 0", function () {
		/** void 0 **/
		var results = [];
		for (var i = 0; i < 10; i++) {
		    var key = '_' + Math.random() + i;
		    (object[key] !== void 0) && results.push(key);
		}
		if (results.length) throw 'wtf?';
	});

	suite.add("hasOwnProperty", function () {
		/** hasOwnProperty **/
		var results = [];
		for (var i = 0; i < 10; i++) {
		    var key = '_' + Math.random() + i;
		    object.hasOwnProperty(key) && results.push(key);
		}
		if (results.length) throw 'wtf?';
	});

	suite.add("object[key]", function () {
		/** object[key] **/
		var results = [];
		for (var i = 0; i < 10; i++) {
		    var key = '_' + Math.random() + i;
		    object[key] && results.push(key);
		}
		if (results.length) throw 'wtf?';
	});

	suite.add("typeof object[key] === undefined", function () {
		/** typeof object[key] === undefined  **/
		var results = [];
		for (var i = 0; i < 10; i++) {
		    var key = '_' + Math.random() + i;
		    typeof object[key] === undefined && results.push(key);
		}
		if (results.length) throw 'wtf?';
	});

	suite.on("cycle", function (evt) {
		console.log(" - " + evt.target);
	});

	suite.on("complete", function (evt) {
		console.log(new Array(30).join("-"));

		var results = evt.currentTarget.sort(function (a, b) {
			return b.hz - a.hz;
		});

		results.forEach(function (item) {
			console.log((idx + 1) + ". " + item);
		});
	});

	console.log("(key in object) vs. (object[key] !== void 0) vs. object.hasOwnProperty(key)");
	console.log(new Array(30).join("-"));
	suite.run();
});
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8"/>
	<title>(key in object) vs. (object[key] !== void 0) vs. object.hasOwnProperty(key)</title>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/benchmark/1.0.0/benchmark.min.js"></script>
	<script src="./suite.js"></script>
	</head>
	<body>
	<h1>Open the console to view the results</h1>
	<h2><code>cmd + alt + j</code> or <code>ctrl + alt + j</code></h2>
	</body>
	</html>
	"use strict";

	(function (factory) {
	if (typeof Benchmark !== "undefined") {
	factory(Benchmark);
	} else {
	factory(require("benchmark"));
	}
	})(function (Benchmark) {
	var suite = new Benchmark.Suite;

	Benchmark.prototype.setup = function () {
	var object = {};
	for (var i = 0; i < 5; i++) {
	object[i + '_' + Math.random()] = Math.random();
	}
	};


	suite.add("in", function () {
	/ in /
	var results = [];
	for (var i = 0; i < 10; i++) {
	var key = '_' + Math.random() + i;
	(key in object) && results.push(key);
	}
	if (results.length) throw 'wtf?';
	});

	suite.add("void 0", function () {
	/ void 0 /
	var results = [];
	for (var i = 0; i < 10; i++) {
	var key = '_' + Math.random() + i;
	(object[key] !== void 0) && results.push(key);
	}
	if (results.length) throw 'wtf?';
	});

	suite.add("hasOwnProperty", function () {
	/ hasOwnProperty /
	var results = [];
	for (var i = 0; i < 10; i++) {
	var key = '_' + Math.random() + i;
	object.hasOwnProperty(key) && results.push(key);
	}
	if (results.length) throw 'wtf?';
	});

	suite.add("object[key]", function () {
	/ object[key] /
	var results = [];
	for (var i = 0; i < 10; i++) {
	var key = '_' + Math.random() + i;
	object[key] && results.push(key);
	}
	if (results.length) throw 'wtf?';
	});

	suite.add("typeof object[key] === undefined", function () {
	/ typeof object[key] === undefined /
	var results = [];
	for (var i = 0; i < 10; i++) {
	var key = '_' + Math.random() + i;
	typeof object[key] === undefined && results.push(key);
	}
	if (results.length) throw 'wtf?';
	});

	suite.on("cycle", function (evt) {
	console.log(" - " + evt.target);
	});

	suite.on("complete", function (evt) {
	console.log(new Array(30).join("-"));

	var results = evt.currentTarget.sort(function (a, b) {
	return b.hz - a.hz;
	});

	results.forEach(function (item) {
	console.log((idx + 1) + ". " + item);
	});
	});

	console.log("(key in object) vs. (object[key] !== void 0) vs. object.hasOwnProperty(key)");
	console.log(new Array(30).join("-"));
	suite.run();
	});