function ajax(params) {
    var http = new XMLHttpRequest();
    http.open("GET",`http://127.0.0.1/back.php?class=${params.data.type}`)
    http.send()
    http.onreadystatechange = function () {
      if(http.readyState == 4 && http.status == 200){
        params.success(JSON.parse(http.response))
      }
    }
  }