添加的代码

var data = [
    { "name" : "Level 2: A", "parent":"Top Level" },
    { "name" : "Top Level", "parent":"null" },
    { "name" : "Son of A", "parent":"Level 2: A" },
    { "name" : "Daughter of A", "parent":"Level 2: A" },
    { "name" : "Level 2: B", "parent":"Top Level" }
    ];

var dataMap = data.reduce(function(map, node)  {
  map[node.name] = node;
  return map;
}, {});

var treeData = [];

 data.forEach(function(node) {
      // add to parent
      var parent = dataMap[node.parent];
      if (parent) {
        // create child array if it doesn't exist
        (parent.children || (parent.children = []))
          // add node to child array
          .push(node);
      } else {
        // parent is null or missing
        treeData.push(node);
      }
    });

如果是以上data 的数据结构，可以转换为 前treeData 的数据结构。