evolve.js

const evolve = (population) => {
  // select individuals for the next generation
  let nextGeneration = selection(population);
  // create the new generation by performing crossover and mutation
  for (let i = 0; i < POPULATION_SIZE; i++) {
    // with probability CROSSOVER_RATE, perform crossover
    if (Math.random() < CROSSOVER_RATE) {
      let individual1 = nextGeneration[i];
      let individual2 = nextGeneration[Math.floor(Math.random() * POPULATION_SIZE)];
      nextGeneration[i] = crossover(individual1, individual2);
    }
    // perform mutation on the individual
    nextGeneration[i] = mutation(nextGeneration[i]);
  }
  // return the new generation
  return nextGeneration;
};