ag-Grid javaScript，TypeError：rowData未定义

ag-Grid，跟随在JavaScript的official demo之后，但使用真实世界的API来处理硬编码数据。注意：不需要jQuery，只需使用原始的纯XMLHttpRequest（）作为ajax。ag-Grid javaScript，TypeError：rowData未定义

F12在相同的结构验证API返回的数据作为演示，内部有孩子节点，gripOptions.rowData分配与返回的数据。
试了实例rowData内的gripOptions作为 rowData: [], 得到了同样的错误，或者 rowData: {},得到的ReferenceError：未定义rowData。

HTML：

<script src="/scripts/agGrid/ag-grid.js"></script> 
<script src="/scripts/agGrid/myAG.js"></script> 
<br />JavaScript ag-Grid 
<div id="myGrid" style="height: 200px;" class="ag-fresh"></div>

myAG.js：

var httpApi = new XMLHttpRequest(); 
var columnDefs = [ 
    { headerName: "Client Name", field: "ClientName", unSortIcon: true, cellRenderer: "group" }, 
    { headerName: "Division", field: "Division" }, 
    { headerName: "Others", field: "Others" } 
]; 
var gridOptions = { 
    columnDefs: columnDefs, 
    getNodeChildDetails: getNodeChildDetails 
}; 

function getNodeChildDetails(rowItem) { 
    if (rowItem.ClientName) { 
     return { 
      group: true, 

     // provide ag-Grid with the children of this group 
      children: rowItem.children, 

      // the key is used by the default group cellRenderer 
      key: rowItem.ClientName 
     }; 
    } else { 
     return null; 
    } 
} 

// wait for the document to be loaded, otherwise 
// ag-Grid will not find the div in the document. 
document.addEventListener("DOMContentLoaded", function() { 
    $.ajax({ 
     type: "GET", 
     url: "/api/myAG/Tree", 
     contentType: "application/json; charset=utf-8", 
     dataType: "json", 
     success: function (data) { 
      gridOptions.rowData = data; 
      var eGridDiv = document.querySelector('#myGrid'); 
      new agGrid.Grid(eGridDiv, gridOptions); 
     }, 
     error: function (XMLHttpRequest, textStatus, errorThrown) { 
      alert(errorThrown); 
     } 
    }) 

});

版本： AG-网格= V8.1.0 火狐= 50.1.0

错误消息：