d3js图例展示问题

Question

我想要展示图谱的颜色图例，但是显示的颜色不正确，连格式也是错误的,求大伙帮我看看哪边错了呗,拜托拜托。

    <script src="http://d3js.org/d3.v3.min.js"></script>
    <script>
      var diameter = 960;
      /*定义一个Tree对象,定义旋转角度和最大半径*/
      var tree = d3.layout.tree().size([360, diameter / 2 - 120]).separation(function(a, b) { return (a.parent == b.parent ? 1 : 2) / a.depth; });
      /*定义布局方向*/
      var diagonal = d3.svg.diagonal.radial().projection(function(d) { return [d.y, d.x / 180 * Math.PI]; });
      /*新建画布，移动到圆心位置*/
      var svg = d3.select("body").append("svg").attr("width", diameter).attr("height", diameter - 150).append("g").attr("transform", "translate(" + diameter / 2 + "," + diameter / 2 + ")");

      d3.json("test2.json", function(error, root) {
        if (error) throw error;
        /*根据数据生成nodes集合，获取node集合的关系集合*/
        var nodes = tree.nodes(root),
        links = tree.links(nodes);

        var link = svg.selectAll(".link").data(links).enter().append("path").attr("class", "link").attr("d", diagonal).style("stroke",function(d){
          if(d.type == 1){/*当前企业*/
            d.level = "#24a6da";
          }else if(d.type == 2){/*股东*/
            d.level = "#4cd1e0";
          }else if(d.type == 3){/*对外投资*/
            d.level = "#92db8c";
          }
          return d.level});

        var node = svg.selectAll(".node").data(nodes).enter().append("g").attr("class", "node").attr("transform", function(d) { return "rotate(" + (d.x - 90) + ")translate(" + d.y + ")"; })

        /*为节点添加圆形标记,如果有子节点为蓝色，否则白色*/
        node.append("circle").attr("r", 6.5).style("fill", function(d) { return d.level; });
/*图例的位置大小*/
  var color_block = level_groups.data('links').append('rect').attr("x", diameter/2 - 60).attr("width",20).attr("height",20).attr("fill",function(d){
    if(d.type == 1){/*当前企业*/
            d.level = "#24a6da";return d.level
          }else if(d.type == 2){/*股东*/
            d.level = "#4cd1e0";return d.level
          }else if(d.type == 3){/*对外投资*/
            d.level = "#92db8c";return d.level
          }});
  var labelText = level_groups.append("text").attr('dx', diameter/2 - 80).attr("dy","18").attr("text-anchor", "end").text(function(d){ return d.type; }).style('stroke',"#000");/*文字末尾对齐，颜色#000*/