Nodejs Utililty Methods Array Pick

Array.prototype.pick = function(){
    var randomIndex = Math.round(Math.random() * (this.length-1))
    return this[randomIndex]

Array.prototype.pick = function () {
  'use strict';
  if (!this.length) {
    return null;
  return this.splice(ROT.RNG.getUniformInt(0, this.length), 1)[0];
};

Array.prototype.pick = function() {
  return this[Math.floor(Math.random()*this.length)];
};

"use strict";
var fs = require("fs"),
    path = require("path");
var charfile = process.argv[2];
var dialogfile = process.argv[3];
var output = process.argv[4];
if (!charfile || !dialogfile || !output) {
    console.error("must provide both character, dialog and output files as params!");
    process.exit(1);
...

Array.prototype.pick = function (callback)
  var element, index, length = this.length;
  for (index = 0; index < length; index++)
    element = this[index];
    if (Array.isArray(element) || (typeof element === 'object')) 
      element.pick(condition);
    if (callback(element,index))
...

Array.prototype.pickRandom = function(){
   return this[Math.floor(Math.random() * this.length)];