Angularjs filter: diff from 2 arrays

diff.js

myApp.filter('diff',function(){
  return function(input,differ){
    if(!differ.length) return input;

    var items = [];
    angular.forEach(input,function(val){
      if( !(val in differ) ){
        items.push(val);
      }
      return items;
    });
  }
});