#Score-based Elo system

Score-based Elo is a rating system similar to classical Elo used in different sports like chess or go, but this calculates ratings by the players' score proportion.

##Installation

In the console:

npm install --save score-based-elo

In node.js:

const elo = require('score-based-elo');

##Usage

• First of all you need to import the package as seen above.

• Create a new Elo system with the EloSystem constructor, with the k factor as an argument:

let eloSystem = new elo(32); //argument is the k factor

k factor can vary depending on the game, in chess is commonly set to 32. More info about Elo system and k factor in this link.

###EloSystem class

• Method eloSystem.getNewElo(player1, player2) Receives two objects representing the players that are competing. player object must have two properties:
• Number player.score, representing the game score obtained.
• Number player.rating, the current Elo rating.

Return the new player1 rating.

• Method eloSystem.setKFactor(number) Reset Elo K factor, a common value is 32. Always returns undefined.

##Example

const elo = require('score-based-elo');

let eloSystem = new elo(32); // k factor

let player1 = {
		score: 800,
		rating: 2000
	},
	player2 = {
		score: 500,
		rating: 2200
	}
;

player1.rating = eloSystem.getNewElo(player1, player2);

// now player1 rating is 2012.0042093450425