Simple bench of basic JS constructs

bench.js

function bench(name, fn) {
	var result;
	// 2 passes to let V8 optimize
	for (var pass = 2; pass >= 0; pass--) {
		var count = 1;
		while (true) {
			var t0 = Date.now();
			fn(count);
			dt = (Date.now() - t0);
			if (dt > 100) {
				result = Math.round(dt * 1000 * 1000 / count);
				break;
			}
			count *= 2;
		}
	}
	console.log(name + "\t" + result + "ns");
}

var DIGITS = "0123456789";


bench(";", function(count) {
	for (var i = count; i > 0; i--) {;
	}
})
bench("x++", function(count) {
	var x = 0;
	for (var i = count; i > 0; i--) {
		x++;
	}
})
bench("f()", function(count) {
	function f() {};
	for (var i = count; i > 0; i--) {
		f();
	}
})
bench("f(1,2,3)", function(count) {
	function f() {};
	for (var i = count; i > 0; i--) {
		f(1, 2, 3);
	}
})
bench("f.call(this)", function(count) {
	function f() {};
	for (var i = count; i > 0; i--) {
		f.call(this);
	}
})
bench("f.apply(this, [])", function(count) {
	function f() {};
	var arr = [];
	for (var i = count; i > 0; i--) {
		f.apply(this, arr);
	}
})
bench("{}", function(count) {
	for (var i = count; i > 0; i--) {
		var foo = {};
	}
})
bench("{a:1,b:2,c:3}", function(count) {
	for (var i = count; i > 0; i--) {
		var foo = {
			a: 1,
			b: 2,
			c: 3
		};
	}
})
bench("new", function(count) {
	for (var i = count; i > 0; i--) {
		var foo = new Object();
	}
})
bench("[]", function(count) {
	for (var i = count; i > 0; i--) {
		var foo = [];
	}
})
bench("[1,2,3]", function(count) {
	for (var i = count; i > 0; i--) {
		var foo = [1, 2, 3];
	}
})
bench("try/catch", function(count) {
	for (var i = count; i > 0; i--) {
		try {} catch (ex) {}
	}
})
bench("try/finally", function(count) {
	for (var i = count; i > 0; i--) {
		try {} finally {}
	}
})
bench("new Error()", function(count) {
	for (var i = count; i > 0; i--) {
		new Error();
	}
})
Error.stackTraceLimit = 0;
bench("new Error() no stack", function(count) {
	for (var i = count; i > 0; i--) {
		new Error();
	}
})

bench("random", function(count) {
	for (var i = count; i > 0; i--) {
		Math.random();
	}
})
bench("exp(2.1)", function(count) {
	for (var i = count; i > 0; i--) {
		Math.exp(2.1);
	}
})
bench("s.length", function(count) {
	for (var i = count; i > 0; i--) {
		DIGITS.length;
	}
})
bench("s[0]", function(count) {
	for (var i = count; i > 0; i--) {
		DIGITS[0];
	}
})
bench("s.charCodeAt(0)", function(count) {
	for (var i = count; i > 0; i--) {
		DIGITS.charCodeAt(0);
	}
})
bench("/\d+/.exec(s)", function(count) {
	for (var i = count; i > 0; i--) {
		/\d+/.exec(DIGITS);
	}
})
bench("RE.exec(s)", function(count) {
	var RE = /\d+/;
	for (var i = count; i > 0; i--) {
		RE.exec(DIGITS);
	}
})
bench("RE capture", function(count) {
	var RE = /(\d+)/;
	for (var i = count; i > 0; i--) {
		RE.exec(DIGITS);
	}
})