For my blog post "6 billion names" (http://wp.me/p1V5ge-1KI)

six-billion-names.js

/**
 * Randomly scrambles the given username.
 * https://gist.github.com/le717/4c2188ca814f56575a26.
 * @param   {String} realName The username to be scrambled.
 * @returns {String} The scrambled username.
 */
function scrambleName(realName) {
  "use strict";

  var newName  = "",
      usedChar = [];

  function randomLetter(myString) {
   return Math.floor(Math.random() * myString.length);
  }

  for (var i = 0; i < realName.length; i++) {
    var letterIndex = randomLetter(realName);

    // That letter has already been used
    while (usedChar.indexOf(letterIndex) > -1) {
      letterIndex = randomLetter(realName);
    }

    usedChar.push(letterIndex);
    newName += realName.charAt(letterIndex);
  }
  return newName;
}

/**
 * Calculate the factorial of a number.
 * http://stackoverflow.com/a/4438167.
 * @param   {Number} x
 * @returns {Number}
 */
function fact(x) {
  "use strict";
 if (x === 0) {
    return 1;
 }
 return x * fact(x - 1);
}

var realName = "jimbobjeffers",
    wanted   = {},
    combos   = fact(realName.length);

for (var i = 0; i < combos; i++) {
  var name = scrambleName(realName);

  // Progress indicator
  if (i % 100 === 0) {
    console.log(i);
  }

  // We are looking for a name with "Bobjim" anywhere in it
  if (name.indexOf("bobjim") > -1) {
    wanted[i] = name;
  }
}

// Report the results.
if (Object.keys(wanted).length === 0) {
  console.log("Bobjim was not found.");
} else {
  console.log(wanted);
}