Hello world example with genetic algorithm

genetic.js

(() => {
  function nArray(n, mapperFn) {
    return new Array(n).join(' ').split(' ').map(mapperFn)
  }

  function getRandomString(length) {
    return nArray(length, e =>
      String.fromCharCode(Math.round(Math.random() * 126))
    ).join('')
  }

  function mutate(previous) {
    var length = previous.length
    var randomIndex = Math.floor(Math.random() * length)
    return previous
      .slice(0, randomIndex)
      .concat(getRandomString(1))
      .concat(previous.slice(randomIndex + 1))
  }

  function selectiveBreed(candidates, ideal, amount) {
    return candidates
      .map(candidate => ({
        distance: candidate.split('').reduce((distance, char, i) => (
          distance += Math.abs(
            ideal.charCodeAt(i) -
            char.charCodeAt(0)
          )
        ), 0),
        original: candidate
      }))
      .sort((a, b) => a.distance - b.distance)
      .slice(0, amount)
      .map(a => a.original)
  }

  function iterate(seed, solution, limit) {
    console.log(seed, limit)
    if (seed === solution) {
      return seed
    }
    if (limit-- > 0) {
      var next = selectiveBreed(
          nArray(100, e => mutate(seed)),
          solution,
          1
        )[0]
      return iterate(
        next,
        solution,
        limit
      )
    }
    return seed
  }
  
  var solution = 'hello world'
  var candidate = iterate(getRandomString(solution.length), solution, 500)
  console.log('candidate', candidate)
})()