codewars上面6kyu的演算法題，下面是演算法題的英文簡介

Your goal in this kata is to implement an difference function, which subtracts one list from another.

It should remove all values from list a, which are present in listb.

difference([1,2],[1]) == [2]

If a value is present in b, all of its occurrences must be removed from the other:

difference([1,2,2,2,3],[2]) == [1,3]

以下是我的解答，可以作為參考

function array_diff(a, b) {
    for(var i=0;i<b.length;i++)
    {
      for(var j=0;j<a.length;j++)
      {
        if(a[j]==b[i]){
          a.splice(j,1);
          j=j-1;
        }
      }
    } 
  return a;
}