d3.geom.quadtree不工作？

Question

下面的代码，然后是console.log。看起来四叉树结构是空的。为什么？。我的代码来自示例 https://www.phase2technology.com/blog/using-d3-quadtrees-to-power-an-interactive-map-for-bonnier-corporation/

 <div class="featurette">
  <img class="featurette-image img-responsive pull-left center-block" src="http://www.placehold.it/400/F84065/000" alt="#">

  <div class="purchase-album">
    <div class="album">
      <img class="img-responsive" src="http://www.placehold.it/200/fa8ca2" />
      <div class="lead">available now:</div>
    </div>
    <div class="space">
    </div>
    <p class="lead text-center available "></p>
    <a href="#" target="_blank">
      <button type="button" class="btn btn-default btn-lg outline" type="submit">iTunes</button>
    </a>

    <a href="#" target="_blank">
      <button class="btn btn-default btn-lg outline" type="submit">loudr</button>
    </a>
  </div>
</div>

<div class="enter">

  <button type="button" class="btn btn-default btn-lg outline" type="submit">
    <a href="#"> enter</a>
  </button>
</div>
</div>

的console.log：

thepoint [23.4183,62.775] iii 0 ....

pointsraw c {：Object} ：Object22.0064,62.714,1：Array [3] 0：22.00641：62.7142：1length：3__proto__：Array [0] 23.65,62.85,3：Array [3] 23.675,62.5236111,5：数组[3] 23.4183,62.775,0：数组[3] 23.7428,62.266,2：数组[3] 23.1977778,62.6272222,4：数组[3] proto ：c

quadtree00对象{leaf：true，nodes：Array [0]，point：null，x：null，y：null} add：（n）find：（n）leaf：truenodes：Array [0] point：nullvisit ：（n）x：nully：null__proto__：Object

所以四叉树似乎是空的，但无法弄清楚原因。非常感谢，谢谢。