Debt snowball vs avalanche: a 40-line JavaScript simulation settles the debate

A personal finance debate over the debt snowball and debt avalanche methods is tested with a month-by-month simulation written in JavaScript. Both approaches pay minimums on every debt and direct surplus cash to one target at a time, with the only difference being whether the smallest balance or highest interest rate is targeted first. The simulation includes safeguards such as a 600-month cap for payments that never catch up and a half-cent threshold to handle floating-point rounding. In a four-debt example with $200 of extra monthly payments, the avalanche method finished in 29 months with $2,860 in interest, versus 30 months and $3,098 for the snowball. The author concludes that paying extra at all matters far more than the choice of method, so people should pick the one they will stick with.