将一条一条的json转成树形结构

tree() {
      var nodes = {
        h0: { id: "h0", name: "root", parent: "root" },
        h1: { id: "h1", name: "第1级", parent: "h0" },
        h2: { id: "h2", name: "第1级", parent: "h0" },
        h3: { id: "h3", name: "第1级", parent: "h0" },
        h4: { id: "h4", name: "第2级1", parent: "h1" },
        h5: { id: "h5", name: "第2级1", parent: "h1" },
        h6: { id: "h6", name: "第2级3", parent: "h3" },
        h7: { id: "h7", name: "第2级3", parent: "h3" },
        h8: { id: "h8", name: "第3级5", parent: "h5" },
        h9: { id: "h9", name: "第3级5", parent: "h5" },
        h10: { id: "h10", name: "第3级5", parent: "h5" },
        h11: { id: "h11", name: "第3级6", parent: "h6" },
        h12: { id: "h12", name: "第3级6", parent: "h6" }
      };
      let trees = [];
      for (var i in nodes) {
        var parentObj = nodes[nodes[i].parent];
        if (parentObj) {
          if (!parentObj['nodeList']) {
            parentObj['nodeList'] = [];
          }
          parentObj['nodeList'].push(nodes[i]);
        } else {
          trees.push(nodes[i]);
        }
      }
      console.log('trees',trees)
      return trees;
}