title: What is the type of "input" parameter in filter function
body: <p>I have written the following custom filters </p>
  
  <p>The HTML code is :</p>
  
  <pre><code>&lt;!DOCTYPE&gt;
  &lt;html&gt;
      &lt;head&gt;
      &lt;/head&gt;
      &lt;body&gt;
          &lt;div ng-app="myApp"&gt;
              &lt;div ng-controller="myCont"&gt;
  
                  &lt;div ng-repeat="b in ar2"&gt;
                      {{b}}
                  &lt;/div&gt;
  
                  {{a}}
                  {{c | myFilt}}
                  &lt;div ng-repeat="x in arr3"&gt;
                      {{x|myFilt}}
                  &lt;/div&gt;
              &lt;/div&gt;
          &lt;/div&gt;
          &lt;script src="jquery-3.0.0.js"&gt;&lt;/script&gt;
          &lt;script src="angular.js"&gt;&lt;/script&gt;
          &lt;script src="angular_try.js"&gt;&lt;/script&gt;
  
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>And the angular js code is :</p>
  
  <pre><code>var myApp = angular.module("myApp",[])
  
  myApp.controller("myCont",["$scope","$filter",function($scope,$filter){
  $scope.a ="pro";
  $scope.arr = ["abc","bcd","cdb"];
  $scope.arr3 = [100,200,300];
  $scope.ar2=[];
  $scope.c = 10;
  for(i in $scope.arr)
  {
  $scope.ar2[i] = $filter("uppercase")($scope.arr[i]);
  }
  }])
  
  
  myApp.filter("myFilt",function(){
  return function(input){
      return input + 20;
  }
  })
  </code></pre>
  
  <p>I wrote the above custom filter to understand angular filters .We can see that this customer filter works both on a number as well on an array. As the "input" parameter of the return function in filter takes both.
  But I was asked in an interview if the filter function can also take object as input . I got confused here and couldn't answer.
  I tried to search online but didn't get any good answer.
       Could someone please help me understand this ?</p>