A function that return an element among other elements based on a set probability for each one

RandomFromProbability.ts

interface ProbabilityProps<T> {
  probability: number;
  value: T;
}

// Input Example:

/* calculateProbability([
    {value: 'Cat', probability: 29},
    {value: 'Dog', probability: 50},
    {value: 'Fish', probability: 20},
    {value: 'Unicorn', probability: 1}
    ])
  */
const calculateProbability = <T>(probabilities: Array<ProbabilityProps<T>>): T => {
  const chance = Math.floor(Math.random() * 100);

  let accumulator = probabilities.reduce((p, c) => p + c.probabilty, 0);

  const mapedChanges: { amount: number; probabilities: number[] }[] = probabilities.map((a) => {
    const toReturn = [accumulator - a.probabilty, accumulator];
    accumulator -= a.probabilty;
    return { value: a.value, probabilities: toReturn };
  });

  for (const data of mapedChanges) {
    const [min, max] = data.probabilities;
    if (chance >= min && chance <= max) {
      return data.value;
    }
  }
  return 0;
};