D3.js强制布局带有外部数据的图形空白

我想从Node.JS服务器为我的部队布局图加载JSON，我尝试了在这个论坛上看到的代码，但它不起作用，我只有一块空白。我不知道为什么它不起作用。这是我的代码：

function makeDraw(){
                var links = [];
                d3.json("./data.json", function(error, json) {
                    links = json.links;
                }).on("load", function () {
                links.forEach(function(link) {
                    link.source = nodes_1[link.source] || (nodes_1[link.source] = {name: link.source, level:link.level, life:link.life});
                    link.target = nodes_1[link.target] || (nodes_1[link.target] = {name: link.target, level:link.level, life:link.life});
                });
                var nodes_1 = {};

                var width_1 = 960,
                        height_1 = 500;
                var force_1 = d3.layout.force()
                        .nodes(d3.values(nodes_1))
                        .links(links)
                        .size([width_1, height_1])
                        .linkDistance(100)
                        .charge(-400)
                        .on("tick", tick)
                        .start();
                var svg_1 = d3.select("body").append("svg")
                        .attr("width", width_1)
                        .attr("height", height_1);
                // Per-type markers, as they don't inherit styles.
                svg_1.append("defs").selectAll("marker")
                        .data(["suit", "licensing", "resolved"])
                        .enter().append("marker")
                        .attr("id", function(d) { return d; })
                        .attr("viewBox", "0 -5 10 10")
                        .attr("refX", 15)
                        .attr("refY", -1.5)
                        .attr("markerWidth", 20)
                        .attr("markerHeight", 20)
                        .attr("orient", "auto")
                        .append("path")
                        .attr("d", "M0,-5L10,0L0,5");
                var path_1 = svg_1.append("g").selectAll("path")
                        .data(force_1.links())
                        .enter().append("path")
                        .attr("class", function(d) { return "link " + d.type; })
                        .style("fill","none").style("stroke","black")
                        .attr("marker-end", function(d) { return "url(#" + d.type + ")"; });

                var circle_1 = svg_1.append("g").selectAll("circle")
                        .data(force_1.nodes())
                        .enter().append("circle")
                        .attr("r", 20)
                        .call(force_1.drag)
                        .style("fill","red")
                        .on("click", click);

                var text_1 = svg_1.append("g").selectAll("text")
                        .data(force_1.nodes())
                        .enter().append("text")
                        .attr("x", 8)
                        .attr("y", ".31em")
                        .text(function(d) { return d.name; });
                // Use elliptical arc path segments to doubly-encode directionality.
                function tick() {
                    path_1.attr("d", linkArc);
                    circle_1.attr("transform", transform);
                    text_1.attr("transform", transform)
                }
                function linkArc(d) {
                    var dx = d.target.x - d.source.x,
                            dy = d.target.y - d.source.y,
                            dr = Math.sqrt(dx * dx + dy * dy);
                    return "M" + d.source.x + "," + d.source.y + "A" + dr + "," + dr + " 0 0,1 " + d.target.x + "," + d.target.y;
                }
                function transform(d) {
                    return "translate(" + d.x + "," + d.y + ")";
                }
            });
            }

谢谢你的帮助！