black-horse/src/models/evaluation-model.js

Chess engine built in Javascript using the alpha-beta algorithm

const pawnTable = [
	[0, 0, 0, 0, 0, 0, 0, 0],
	[10, 10, 0, -10, -10, 0, 10, 10],
	[5, 0, 0, 5, 5, 0, 0, 5],
	[0, 0, 10, 20, 20, 10, 0, 0],
	[5, 5, 5, 10, 10, 5, 5, 5],
	[10, 10, 10, 20, 20, 10, 10, 10],
	[20, 20, 20, 30, 30, 20, 20, 20],
	[0, 0, 0, 0, 0, 0, 0, 0],
];
const knightTable = [
	[0, -10, 0, 0, 0, 0, -10, 0],
	[0, 0, 0, 5, 5, 0, 0, 0],
	[0, 0, 10, 10, 10, 10, 0, 0],
	[0, 0, 10, 20, 20, 10, 5, 0],
	[5, 10, 15, 20, 20, 15, 10, 5],
	[5, 10, 10, 20, 20, 10, 10, 5],
	[0, 0, 5, 10, 10, 5, 0, 0],
	[0, 0, 0, 0, 0, 0, 0, 0],
];
const bishopTable = [
	[0, 0, -10, 0, 0, -10, 0, 0],
	[0, 0, 0, 10, 10, 0, 0, 0],
	[0, 0, 10, 15, 15, 10, 0, 0],
	[0, 10, 15, 20, 20, 15, 10, 0],
	[0, 10, 15, 20, 20, 15, 10, 0],
	[0, 0, 10, 15, 15, 10, 0, 0],
	[0, 0, 0, 10, 10, 0, 0, 0],
	[0, 0, 0, 0, 0, 0, 0, 0],
];
const rookTable = [
	[0, 0, 5, 10, 10, 5, 0, 0],
	[0, 0, 5, 10, 10, 5, 0, 0],
	[0, 0, 5, 10, 10, 5, 0, 0],
	[0, 0, 5, 10, 10, 5, 0, 0],
	[0, 0, 5, 10, 10, 5, 0, 0],
	[0, 0, 5, 10, 10, 5, 0, 0],
	[25, 25, 25, 25, 25, 25, 25, 25],
	[0, 0, 5, 10, 10, 5, 0, 0],
];
const queenTable = [
	[0, 0, -10, 0, 0, -10, 0, 0],
	[0, 0, 0, 10, 10, 0, 0, 0],
	[0, 0, 10, 15, 15, 10, 0, 0],
	[0, 10, 15, 20, 20, 15, 10, 0],
	[0, 10, 15, 20, 20, 15, 10, 0],
	[0, 0, 10, 15, 15, 10, 0, 0],
	[25, 25, 25, 25, 25, 25, 25, 25],
	[0, 0, 0, 0, 0, 0, 0, 0],
];
const kingTable = [
	[0, 5, 5, -10, -10, 0, 10, 5],
	[-30, -30, -30, -30, -30, -30, -30, -30],
	[-50, -50, -50, -50, -50, -50, -50, -50],
	[-70, -70, -70, -70, -70, -70, -70, -70],
	[-70, -70, -70, -70, -70, -70, -70, -70],
	[-70, -70, -70, -70, -70, -70, -70, -70],
	[-70, -70, -70, -70, -70, -70, -70, -70],
	[-70, -70, -70, -70, -70, -70, -70, -70],
];
const kingEndGameTable = [
	[-50, -10, 0, 0, 0, 0, -10, -50],
	[-10, 0, 10, 10, 10, 10, 0, -10],
	[0, 10, 20, 20, 20, 20, 10, 0],
	[0, 10, 20, 20, 20, 20, 10, 0],
	[0, 10, 20, 20, 20, 20, 10, 0],
	[0, 10, 20, 20, 20, 20, 10, 0],
	[-10, 0, 10, 10, 10, 10, 0, -10],
	[-50, -10, 0, 0, 0, 0, -10, -50],
];

const bishopPairBonus = 30;
const endGameValue = 51400;
const doubledPawnPenalty = 10;
const isolatedPawnPenalty = 10;
const castlingPenalty = 99;
const castlingEndGamePenalty = 0;
const castlingBonus = 0;

module.exports = class EvaluationModel {
	constructor() {}

	pawnScore(row, column) {
		return pawnTable[row][column];
	}

	knightScore(row, column) {
		return knightTable[row][column];
	}

	bishopScore(row, column) {
		return bishopTable[row][column];
	}

	rookScore(row, column) {
		return rookTable[row][column];
	}

	queenScore(row, column) {
		return queenTable[row][column];
	}

	kingScore(row, column) {
		return kingTable[row][column];
	}

	kingEndGameScore(row, column) {
		return kingEndGameTable[row][column];
	}

	bishopPairBonus() {
		return bishopPairBonus;
	}

	doubledPawnPenalty() {
		return doubledPawnPenalty;
	}

	isolatedPawnPenalty() {
		return isolatedPawnPenalty;
	}

	castlingPenalty() {
		return castlingPenalty;
	}

	castlingEndGamePenalty() {
		return castlingEndGamePenalty;
	}

	castlingBonus() {
		return castlingBonus;
	}

	endGameValue() {
		return endGameValue;
	}
};