XMLHttpRequest不包含GET请求

Question

我尝试使用XMLHttpRequest检索JSON数据，但似乎不会包含任何我的字段数据。

var fields = ["ID", "item_id", "item_tag", "item_name", "item_default_price", "item_quantity", "item_comment"];

function loadTable(json_items) {
  alert(json_items);
}

var frm = document.querySelector("form.inventory-search-form");
frm.onsubmit = function(event) {
  event.preventDefault();

  var request = new XMLHttpRequest();
  request.onreadystatechange = function () {
      var DONE = this.DONE || 4;
      if (this.readyState === DONE && this.status == 200){
        try {
          loadTable(JSON.parse(this.responseText));
        } catch(err) {

        }
      }
  };

  request.open('GET', '/api/inventory/list', true);
  request.setRequestHeader('X-Requested-With', 'XMLHttpRequest');  // Tells server that this call is made for ajax purposes.
                                                                   // Most libraries like jQuery/Prototype/Dojo do this
  var data = new FormData(frm);
  for (i=0; i<fields.length; i++) {
    data.append(fields[i], frm.querySelector("[name='" + fields[i] + "']").value);
  }

  request.send(data);
}

frm.onsubmit(document.createEvent("Event"));

我做错了什么？

我已检查FormData并且其中包含字段，但它没有提供所需的GET请求，例如/api/inventory/list?ID=2，而是仅发出/api/inventory/list。

谢谢！