http://www.freecodecamp.com/patrickcurl 's solution for Bonfire: Smallest Common Multiple

bonfire-smallest-common-multiple.js

// Bonfire: Smallest Common Multiple
// Author: @patrickcurl
// Challenge: http://www.freecodecamp.com/challenges/bonfire-smallest-common-multiple
// Learn to Code at Free Code Camp (www.freecodecamp.com)

function smallestCommons(arr) {
  range = toRange(arr);
  return range.reduce(function(a, b) {
        return lcm(a, b);
    });
}
function lcm(a, b) 
{
  return (Math.abs(a * b) / gcd(a, b));
}
 
function gcd(a, b) {
  var temp;
  while (b != 0) {
    temp = b;
    b = a % b;
    a = temp;
  }
  return a;
}

function toRange(arr){
  var r = [];
  var end = arr.reduce(function(a,b){
    return Math.max(a,b);
  });
  var start = arr.reduce(function(a, b) {
    return Math.min(a, b);
  });
  for (var i = start; i <= end; i++) {
    r.push(i);
  }
  return r;
}


smallestCommons([1,5]);