Uncaught TypeError: $.ajax is not a function at :10:4

Question

PS: I am using dummy url for posting on public platform perspective

var plan;
var settings = {
  "url": "https://benefits-pas-stage.abc.com/PlanAvailability/web/facilities/100/plans/medical",
  "method": "GET",
  "timeout": 0,
  "headers": {
    "Authorization": "UGxhbkF2YWlsYWJpbGl0eVRvb2wyMDE3MDI="
  },
};
 $.ajax(settings).done(function (response) {
   plan = response;
console.log(response);
});