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';
import type { Game, GameKind } from '@echecs/progressive';

// games[n] = round n+1; Game has no `round` field
const games: Game[][] = [
  [{ black: 'B', result: 1, white: 'A' }], // round 1 → running: 1
  [{ black: 'C', result: 0.5, white: 'A' }], // round 2 → running: 1.5
  [{ black: 'A', result: 0, white: 'D' }], // round 3 → running: 1.5
  // Unplayed rounds use kind to classify the bye type
  [{ black: '', kind: 'half-bye', result: 0.5, white: 'A' }], // round 4 → running: 2
];

const score = progressive('A', games);
// 1 + 1.5 + 1.5 + 2 = 6

API

All functions accept (playerId: string, games: Game[][], players?: Player[]) and return number. Round is determined by array position: games[0] = round 1, games[1] = round 2, etc. The Game type has no round field. The optional kind?: GameKind field on Game identifies unplayed rounds (byes score their awarded points for the running total).

progressive(playerId, games, players?)

FIDE section 7.5 — Progressive score. Accumulates the player's running score after each round, then sums all those running totals. Rounds are processed in array order (games[0] = round 1). 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, players?)

FIDE section 7.5 — Progressive score excluding the first round. Computes the progressive score starting from round 2 (games[1]), 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.