$.extend({ 
  password: function (length, special) {
    var iteration = 0;
    var password = "";
    var randomNumber;
    if(special == undefined){
        var special = false;
    }
    while(iteration < length){
        randomNumber = (Math.floor((Math.random() * 100)) % 94) + 33;
        if(!special){
            if ((randomNumber >=33) && (randomNumber <=47)) { continue; }
            if ((randomNumber >=58) && (randomNumber <=64)) { continue; }
            if ((randomNumber >=91) && (randomNumber <=96)) { continue; }
            if ((randomNumber >=123) && (randomNumber <=126)) { continue; }
        }
        iteration++;
        password += String.fromCharCode(randomNumber);
    }
    return password;
  }
});

// How to use
$.password(8);
$.password(12, true);