Password generator using ES5 JavaScript and the Fisher-Yates Algorithm

PasswordGenerator-ES5.js

var config = {
    numberToInclude: {
        lowers : 3,
        uppers : 2,
        digits : 2,
        symbols: 2
    },
    digits: "23456789",
    symbols: "@#$%&*()[]~=",
    lowers: "abcdefghjkmnpqrstuvwxyz",
    uppers: "ABCDEFGHJKMNPQRSTUVWXWZ"
};

/**
 * Randomize an array using the Fisher-Yates Algorithm method. 
 * 
 */
var randomizeArray = function( element, index, array ) {
    var pos = Math.floor( Math.random() * index );
    var old = array[index];
    var rand = array[pos];

    array[index] = rand;
    array[pos] = old;
};

/**
 * Arrays to hold all the candidates for the password
 */
var digits  = config.digits.split("");
var symbols = config.symbols.split("");
var lowers  = config.lowers.split("");
var uppers  = config.uppers.split("");

/**
 * Randomize the candidate arrays
 */
digits.forEach( randomizeArray );
symbols.forEach( randomizeArray );
lowers.forEach( randomizeArray );
uppers.forEach( randomizeArray );

/**
 * Construct the password array with the configured number of elements from
 * each array
 */
var passwordArray = []
    .concat( lowers.slice (0, config.numberToInclude.lowers)  )
    .concat( uppers.slice (0, config.numberToInclude.uppers)  )
    .concat( digits.slice (0, config.numberToInclude.digits)  )
    .concat( symbols.slice(0, config.numberToInclude.symbols) )
    ;

/**
 * Randomize the final array
 */
passwordArray.forEach( randomizeArray );

/**
 * Transform to a string and return it
 */
var password = passwordArray.join("");

console.log(password);