foreach-bench.js

#!/usr/bin/env node-bench


var list = [
  "foo",
  "bar",
  "baz",
  "quux",
  "asdf",
  "qwerty",
  "bonk",
  "whack",
  "zoom",
  "zap"
];

exports.compare = {
  forEach : function () {
    var len = 0;
    list.forEach(function (item) {
      len += item.length;
    });
  },
  length : function () {
    for (var len = 0, i = 0; i < list.length; i ++) {
      len += list[i].length;
    }
  },
  lengthCached : function () {
    for (var len = 0, i = 0, l = list.length; i < l; i ++) {
      len += list[i].length;
    }
  },
  lengthWithFn : function () {
    function f (l) { len += l };
    for (var len = 0, i = 0; i < list.length; i ++) {
      f(list[i].length);
    }
  }
};

output.txt

[14:29:55 9435] $ ./foreach-bench.js 
benchmarking /Users/isaacs/Documents/src/js/node-playground/foreach-bench
Please be patient.
Scores: (bigger is better)

lengthCached
Raw:
 > 3292.292292292292
 > 8358
 > 8361
Average (mean) 6670.43076409743

length
Raw:
 > 5954
 > 6228
 > 6061
Average (mean) 6081

lengthWithFn
Raw:
 > 3088.911088911089
 > 3072
 > 3098
Average (mean) 3086.303696303696

forEach
Raw:
 > 2220.3389830508477
 > 2561.4385614385615
 > 2542
Average (mean) 2441.2591814964694

Winner: lengthCached
Compared with next highest (length), it's:
8.84% faster
1.1 times as fast
0 order(s) of magnitude faster

Compared with the slowest (forEach), it's:
63.4% faster
2.73 times as fast
0 order(s) of magnitude faster