Progressive

Progressive is a TypeScript library implementing the Progressive Score tiebreak for chess tournaments, following the FIDE Tiebreak Regulations (section 7.5). Zero runtime dependencies.

Installation

npm install @echecs/progressive

Quick Start

import { progressive } from '@echecs/progressive';

const games = [
  { blackId: 'B', result: 1, round: 1, whiteId: 'A' }, // A wins → running: 1
  { blackId: 'C', result: 0.5, round: 2, whiteId: 'A' }, // draw → running: 1.5
  { blackId: 'A', result: 0, round: 3, whiteId: 'D' }, // A loses → running: 1.5
];

const score = progressive('A', games);
// 1 + 1.5 + 1.5 = 4

API

All functions accept (playerId: string, games: Game[]) and return number. They are drop-in compatible with the shared Tiebreak type (playerId: string, games: Game[], players: Player[]) => number.

progressive(playerId, games)

FIDE section 7.5 — Progressive score. Accumulates the player's running score after each round, then sums all those running totals. Games are sorted by round number before accumulating. A player who scores 1, 0.5, 1 across three rounds produces a progressive score of 1 + 1.5 + 2.5 = 5.

progressiveCut1(playerId, games)

FIDE section 7.5 — Progressive score excluding the first round. Computes the progressive score starting from round 2, skipping the first round's result entirely. Returns 0 when no games have been played.

Contributing

Contributions are welcome. Please open an issue at github.com/mormubis/progressive/issues.