Algorithms: Find the Symmetric Difference

JavaScript
1 
function sym(...args) {
  console.log(args);
  console.log(args.length);
  var k =0
  while(k!=1){
    var arr4 = compare(args[0],args[1])
    args= args.slice(2)
    k++
  }
  return arr4.sort()
}
function compare(arr1,arr2){
  var arr3=[]
  arr3=arr1
  arr3=arr3.concat(arr2)
  
console.log('begin array: '+arr3)
  for(i=0;i<arr3.length;i++){
    for(j=i+1;j<arr3.length;j++){
      if(arr3[i]==arr3[j]){
        arr3.splice(j,1)
        arr3.splice(i,1)
        i=-1
        break;
      }
    }
  }
  return arr3
}

sym([1, 2, 3], [5, 2, 1, 4])

Hi I’m not sure what’s wrong with my code? for the problem set: ’ Algorithms: Find the Symmetric Difference’