JSFiddle - React, Tailwind, and code Playground

JavaScript

values = {};
values['mpsRegnomer'] = 1;
values['mpsMarka'] = 2;
values['mpsMarkaOther'] = 3;
values['engineType'] = 4;

console.log(JSON.stringify(values));

$.ajax({
  type: 'POST',
  url: 'assets/clients/services/saveDataMPS.php',
  async: false,
  dataType: "JSON",
  data: {"values": JSON.stringify(values)},
  success:function(response){
    alert(1);
  }
});