find least common multiple of all numbers in a range.

leastCommonMultiple.js

function smallestCommons(arr) {
  arr.sort(function(a,b) {
    return b-a;
  });
  var min = arr[1];
  var max = arr[0];
  var allPrimeFactors = [];
  var availablePrimes = [];
  var reducedFactors = [];
  var poweredFactors = [];
  var result = 0;
  for(var i=min; i<=max; i++) {
    allPrimeFactors.push(getPrimeFactors(i));
  }
  availablePrimes = allPrimeFactors.reduce(function(prev,curr) {
    for (var i=0; i<curr.length;i++) {
      if (prev.indexOf(curr[i]) === -1) {
        prev.push(curr[i]);
      }
    }
    return prev;
  }, [])
  for(var i=0; i<availablePrimes.length; i++) {
    var currentPrime = availablePrimes[i];
    var finalCount = 0;
    for (var i1=0; i1<allPrimeFactors.length; i1++) {
      var currentFactors = allPrimeFactors[i1];
      var currentCount = 0;
      if (currentFactors.indexOf(currentPrime) > -1) {
        for(var i2=0; i2<currentFactors.length; i2++) {
          if (currentFactors[i2] === currentPrime) {
            currentCount += 1;
          }
        }
      }
      if(currentCount > finalCount) {
        finalCount = currentCount;
      }
    }
    poweredFactors.push(Math.pow(currentPrime,finalCount));
  }
  result = poweredFactors.reduce(function(prev,curr) {
    return prev*curr;
  })
  return result;
}

function getPrimeFactors(num) {
  var primes = findPrimes(num);
  var remainder = num;
  var results = [];
  while(primes.indexOf(remainder) === -1 && remainder > 1) {
    for(var i=0; i<primes.length && remainder > 1; i++) {
      var prime = primes[i];
      while(remainder % prime === 0) {
        results.push(prime);
        remainder /= prime;
      }
    }
  }
  if (remainder > 1) {
    results.push(remainder);
  }
  return results;
}

function findPrimes(max) {
  var possibles = [];
  var i = 0;
  for (i=2; i<=max; i++) {
    possibles.push(i);
  }
  for(i=0;i<possibles.length;i++) {
    var current = possibles[i];
    var product = 0;
    for(var i1=current; product<=max; i1++) {
      product = current*i1;
      var index = possibles.indexOf(product);
      if (index > -1) {
        possibles.splice(index, 1);
      }
    }
  }
  return possibles;
}