fast-balance

Exact, fast stoichiometric equation balancing for JavaScript and TypeScript.
Conservation of mass and charge are solved with BigInt rational arithmetic — no floating-point discrepancy, ever.

Features

• Exact arithmetic — the balancing kernel uses BigInt rationals, so results are always the smallest exact integer coefficients.
• Linear-time core — element symbols are validated against a fixed set, so elimination is O(m²·n) with m = O(1): linear in the number of species.
• Real chemistry — nested ()/[], ionic charges, hydrates, state symbols, isotopes, nuclear mode, functional groups and common abbreviations.
• Spectator species — a species on both sides is balanced, not rejected (C3H8 + O2 + N2 -> CO2 + H2O + N2).
• Underdetermined systems — the minimal positive solution is returned and flagged; balanceAll returns every independent balance.
• Honest errors — typed BalanceError with stable codes; unknown elements, ambiguous input and unbalanceable equations are reported explicitly.
• Small and tree-shakeable — zero runtime dependencies, dual ESM/CommonJS build, TypeScript types, and "sideEffects": false so…