collectionPerf.js

var go = (function (size, iterations) { 

var l = size || 33;
var k = "A";
var j = k.charCodeAt(0);
var i = 0;

var m = j;
var n = null;

var arr = []; // array with numeric index
var obj = {}; // object with non-numeric key
var seq = {}; // object with numeric key

var alpha = new Function ();
var omega = new Function ();

for (i = 0; i < l; i++) {
	arr[i] = i;
	alpha[i] = i;
	seq[i] = i;

	k = String.fromCharCode(j++);

	obj[k] = i;
	omega[k] = i;
}

n = j;



var log = (typeof console === "undefined" ? print : function () {
	console.log.apply(console, arguments);
});

var s;
var reps = iterations || 100000;
var r = 0;
var q; // key index
var p; // key count
var o; // object keys
var t;

t = Date.now();

log(l+" (key/index count)");
log(reps+" (read/write repetitions)");
log("Array JSON -- "+JSON.stringify(arr));
log("Object JSON -- "+JSON.stringify(obj));

//return;

for (r = 0; r < reps; r++) {
	for (i = 0; i < l; i++) {
		s = arr[i];
		arr[i] = s + 1;
	}
}

log((Date.now() - t)+" (arr with index)"), (t = Date.now());

for (r = 0; r < reps; r++) {
	for (i = 0; i < l; i++) {
		s = alpha[i];
		alpha[i] = s + 1;
	}
}

log((Date.now() - t)+" (alpha with index)"), (t = Date.now());

for (r = 0; r < reps; r++) {
	for (k in obj) {
		s = obj[k];
		obj[k] = s + 1;
	}
}

log((Date.now() - t)+" (obj with indirect key)"), (t = Date.now());

for (r = 0; r < reps; r++) {
	for (k in omega) {
		s = omega[k];
		omega[k] = s + 1;
	}
}

log((Date.now() - t)+" (omega with indirect key)"), (t = Date.now());

for (r = 0; r < reps; r++) {
	o = Object.keys(obj);
	p = o.length;
	q = 0;
	for (q = 0; q < p; q++) {
		k = o[q];
		s = obj[k];
		obj[k] = s + 1;
	}
}

log((Date.now() - t)+" (obj with direct key)"), (t = Date.now());

for (r = 0; r < reps; r++) {
	o = Object.keys(omega);
	p = o.length;
	q = 0;
	for (q = 0; q < p; q++) {
		k = o[q];
		s = omega[k];
		omega[k] = s + 1;
	}
}

log((Date.now() - t)+" (omega with direct key)"), (t = Date.now());

o = Object.keys(obj);
p = o.length;
for (r = 0; r < reps; r++) {
	q = 0;
	for (q = 0; q < p; q++) {
		k = o[q];
		s = obj[k];
		obj[k] = s + 1;
	}
}

log((Date.now() - t)+" (obj with direct key -- explicitly hoisted loop-invariants for comparison)"), (t = Date.now());

for (r = 0; r < reps; r++) {
	for (i = 0; i < l; i++) {
		s = seq[i];
		seq[i] = s + 1;
	}
}

log((Date.now() - t)+" (seq with index)"), (t = Date.now());

for (r = 0; r < reps; r++) {
	for (k in seq) {
		s = seq[k];
		seq[k] = s + 1;
	}
}

log((Date.now() - t)+" (seq with indirect key)"), (t = Date.now());

for (r = 0; r < reps; r++) {
	o = Object.keys(seq);
	p = o.length;
	q = 0;
	for (q = 0; q < p; q++) {
		k = o[q];
		s = seq[k];
		seq[k] = s + 1;
	}
}

log((Date.now() - t)+" (seq with direct key)"), (t = Date.now());

log(""); // arbitrary space

/*

go(15, 1000000)
15 (key/index count)
1000000 (read/write repetitions)
Array JSON -- [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14]
Object JSON -- {"A":0,"B":1,"C":2,"D":3,"E":4,"F":5,"G":6,"H":7,"I":8,"J":9,"K":10,"L":11,"M":12,"N":13,"O":14}
160 (arr with index)
162 (alpha with index)
1316 (obj with indirect key)
1358 (omega with indirect key)
1774 (obj with direct key)
1773 (omega with direct key)
1325 (obj with direct key -- explicitly hoisted loop-invariants for comparison)
156 (seq with index)
2495 (seq with indirect key)
1830 (seq with direct key)

go(16, 1000000)
16 (key/index count)
1000000 (read/write repetitions)
Array JSON -- [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]
Object JSON -- {"A":0,"B":1,"C":2,"D":3,"E":4,"F":5,"G":6,"H":7,"I":8,"J":9,"K":10,"L":11,"M":12,"N":13,"O":14,"P":15}
170 (arr with index)
172 (alpha with index)
3086 (obj with indirect key)
3131 (omega with indirect key)
2055 (obj with direct key)
1993 (omega with direct key)
1386 (obj with direct key -- explicitly hoisted loop-invariants for comparison)
164 (seq with index)
2635 (seq with indirect key)
1900 (seq with direct key)

*/

});

go(33, 100000);