filterable.extra Boolean (default: true)

If set to true the filter menu allows the user to input a second criterion.

Example - disable the extra filtering criteria

<div id="grid"></div>
<script>
$("#grid").kendoGrid({
  columns: [
    { field: "name" },
    { field: "age" }
  ],
  filterable: {
    extra: false
  },
  dataSource: {
   data: [
    { id: 1, name: "Jane Doe", age: 30 },
    { id: 2, name: "John Doe", age: 33 }
   ],
   schema:{
    model: {
     id: "id",
     fields: {
       age: { type: "number"}
     }
    }
   }
  }
});
</script>