Call Faye: Texas hold 'em helper

See the blog post, Learning about risk, for kids and grownups, but in a nutshell, this repository contains

a Texas hold 'em hand anumerator and analyzer, and
a web application to facilitate in-person poker play by showing players their odds as they deal cards—you have to track bets and folds yourselves in meatspace. Easy to deploy on your own cheap web server solution.

Play at https://callfaye.glitch.me/.

Here's what the app looks like, with three browsers standing in for three users:

To play:

Familiarize yourself with Texas hold 'em basics: Pagat
Go to https://callfaye.glitch.me/
(open multiple tabs if you don't have a friend handy)
Get everyone to enter the same table name
Get everyone to click 'Announce'
All players will see each other
Anyone can deal cards by clicking the appropriate button
Your hand's probabilities for each final hand ranking will be printed out in a table
Your probabilities will be accompanied by other players' probabilities for each rankings also (taking into account the fact that they can't have your pocket cards)
You and your friends take care of betting and folding.

Installation and run

Ensure you have both Git and Node.js installed. Then run the following set of commands in your command-line prompt (i.e., Terminal in macOS, xterm in Linux, Command Prompt in Windows, etc.):

git clone https://github.com/fasiha/hold-em-tools.git
cd hold-em-tools
npm install
npm run build

The git command comes from the eponymous program you have installed, while npm was installed by Node.js.

Then, to start the Call Faye server, run

npm run start

To run on Glitch, simply clone this repository and it should work.

Dev

Beckend serve

The server runs a Socket.io server that just connects together clients at the same poker table. It knows absolutely nothing about poker.

Frontend client

The frontend is a MobX & React app, residing in client.ts. It leverages playerHelper.ts to compute probabilities of final hand rankings at each point in the game, either using the pre-computed data or re-computing on the fly. It requires pre-computed enumerations of final hand rankings' probabilities for all 2- and 3-card combinations, because these take too long to compute on the fly. These are included in the repository, but if you want to regenerate them, run

node skinnyRank.js

This will recreate map-r-7-n-2.json and map-r-7-n-3.json. It might take several hours, but only has to be done once.

Each client sends and receives messages to the table, which the backend shares with all other players. The user who clicks "Deal flop" generates a random seed that is shared with all other players. So each player's client knows what cards others have but just hides it from them until the showdown. This works well for local games, where you can trust all players to not run custom JavaScript code and cheat.