How to convert json to pojo class

Ionic Framework
1

How i can convert get/post response json into pojo class

for example i have a json like this

{
"popup": {
    "menuitem": [
      {"value": "New", "onclick": "CreateNewDoc"},
      {"value": "Open", "onclick": "OpenDoc"},
      {"value": "Close", "onclick": "CloseDoc"}
    ]
  }
}

and i have a pojo class Example.ts

declare module Example {

    export interface Menuitem {
        value: string;
        onclick: string;
    }

    export interface Popup {
        menuitem: Menuitem[];
    }

    export interface RootObject {
        popup: Popup;
    }
}

what should i write in success funtion so the above response convert automatically into Example.ts

$.ajax({
               url:'URL',
                      type: "GET",
      success : function(responseText)
      {
    alert(JSON.stringify(responseText));
      },
    error: function(XMLHttpRequest, textStatus, errorThrown)
    {
        alert("Status: " + textStatus);
    }
    });