symmetric diff bonfire (WIP)

gistfile1.txt

function sym(arr) {
  //get args
  var args = Array.prototype.slice.call(arguments);
  
  //symmetric difference is the union minus the intersection
  
  
  //find the union with no duplicates
  function findUnion (arr1, arr2) {
    var union = (arr1.concat(arr2)).sort();
    //steps through the values to remove dups
    for (var i = union[0]; i < union[union.length-1]; i++) {
      //for each value, are there duplicates?
      if (union.indexOf(i) >= 0) {
        if (union.indexOf(i) !== union.lastIndexOf(i)) {
          // remove all but the first one
          var firstIndex = union.indexOf(i);
          var howMany = (union.lastIndexOf(i) - firstIndex);
          union.splice(firstIndex+1, howMany);
        }
      }
    }
    return union;
  }
  
  function findIntersection (arr1, arr2) {
  //find the intersection
    var intersection = [];
    //step through arr1, looking for each element in arr2
    arr1.forEach(function(value, index) {
      if (compare(value, arr2)>=0) {
        if (intersection.indexOf(value)) {
          intersection.push(value);
        }
      }
    });
    // helper function for above
    function compare(value, arr) {
      return (arr.indexOf(value) >= 0);
    }
    return intersection;
  }
  
  var union = findUnion(args[0], args[1]);
  var intersection = findIntersection(args[0], args[1]);
  console.log(union, intersection);
  var symmDiff;
  //filter union for intersection to return symm diff
  symmDiff = union.filter(function(value, index) {
    console.log(intersection.indexOf(value));
    return (intersection.indexOf(value) < 0);
  });
  
  
  return symmDiff;
}

sym([1, 1], [1]);