Use An If-else Statement Within A Sentinel Controlled Loop Plan?

I am attempting to set up a very basic menu to drive a program for two different games. I need the menu to process using a primed sentinel controlled loop (where the quit option is the sentinel). I have already set up a function for each game and was hoping to call the function when the user selects a game. I also want to both (a) keep a count of the number of games played and (b) keep a points score, which is to be displayed before the menu is shown agin. When the user quits, I want the final number of points and games played written to document body. I have only very basic knowledge of JavaScript so I realise this is probably a simple answer but I've spent a heap of time on it so far and the menu still has glitches.

This is what I have so far:

SENTINEL = 0;
MESSAGE_MENU = 'Menu: 1. Pattern Game, 2. Guessing Game, 0. Quit'
userInput = parseInt(prompt(MESSAGE_MENU));
while(userInput != SENTINEL) {

[Code]....