CRSF Token in SharePoint Web Service Request

requestdigest

var formDigestValue = $("#__REQUESTDIGEST").val();

$.ajax({
  headers: { "X-RequestDigest": formDigestValue },
  url: url,
  method: "POST",
  contentType: "application/json",
  data: JSON.stringify(data),
  success: success,
  error: error
  });