count.js

#!/usr/bin/env node

String.prototype.count = function(s) {
  var n = 0, i = 0;
  while ((i = this.indexOf(s, i) + 1) != 0) n++;
  return n;
}

function count(str, what) {
  var n = 0, i = 0;
  while ((i = str.indexOf(what, i) + 1) != 0) n++;
  return n;
}

var tasty = "jelly", l = "l";

exports.compare = {
  "prototype": function() {
    tasty.count(l);
  },
  "plain": function() {
    count(tasty, l);
  }
};

require("bench").runMain();

/*
benchmarking count.js
Please be patient.
Scores: (bigger is better)

plain
Raw:
 > 1485.5144855144856
 > 1457.5424575424574
 > 1463.5364635364635
 > 1470.5294705294705
 > 1416.5834165834167
Average (mean) 1458.741258741259

prototype
Raw:
 > 620.3796203796204
 > 644.7105788423154
 > 643.7125748502993
 > 649.3506493506494
 > 650.3496503496503
Average (mean) 641.7006147545069

Winner: plain
Compared with next highest (prototype), it's:
56.01% faster
2.27 times as fast
0.36 order(s) of magnitude faster
*/