shuson

$.ajax({
  type: "GET",
  url: "imageURL",
  beforeSend: function (xhr) {
    xhr.overrideMimeType('text/plain; charset=x-user-defined');
  },
  success: function (result, textStatus, jqXHR) {       
    if(result.length < 1){
        alert("The thumbnail doesn't exist");
        $("#thumbnail").attr("src", "data:image/png;base64,");