Birthday problem collision calculator in javascript

birthday-problem.js

/**
 *  @param p {number} - The total number of different possibilities (days in a year)
 *  @param n {number} - The number of occurrences (number of people)
 *  @returns {number} - The probability of at least two people having the same birthday. @min 0 - @max 1 
 */

export const birthday_problem = (p, n) => {
  let acc = 1;
  for(let i = 1; i < n; i++) {
    acc *= (1 - ( i / p ));
  }
  return 1 - acc;
}