d3.js how to dynamically add nodes to a tree

Question

I am using a d3.js tree, and would like to add nodes dynamically, rather than pre-loading the entire tree.

How would i modify the following in order to dynamically add additional JSON nodes when a node is clicked? (see link below, and code below)

http://mbostock.github.com/d3/talk/20111018/tree.html

So rather than pre-loading the entire tree, instead i would like to retrieve the child nodes only when the parent is clicked. I can retrieve the json for the child nodes in the toggle function, however i can't figure out how i can add them to the tree.

var m = [20, 120, 20, 120],     w = 1280 - m[1] - m[3],     h = 800 - m[0] - m[2],     i = 0,     root;  var tree = d3.layout.tree()     .size([h, w]);  var diagonal = d3.svg.diagonal()     .projection(function(d) { return [d.y, d.x]; });  var vis = d3.select("#body").append("svg:svg")     .attr("width", w + m[1] + m[3])     .attr("height", h + m[0] + m[2])   .append("svg:g")     .attr("transform", "translate(" + m[3] + "," + m[0] + ")");  d3.json("flare.json", function(json) {   root = json;   root.x0 = h / 2;   root.y0 = 0;    function toggleAll(d) {     if (d.children) {       d.children.forEach(toggleAll);       toggle(d);     }   }    // Initialize the display to show a few nodes.   root.children.forEach(toggleAll);   toggle(root.children[1]);   toggle(root.children[1].children[2]);   toggle(root.children[9]);   toggle(root.children[9].children[0]);    update(root); });  function update(source) {   var duration = d3.event && d3.event.altKey ? 5000 : 500;    // Compute the new tree layout.   var nodes = tree.nodes(root).reverse();    // Normalize for fixed-depth.   nodes.forEach(function(d) { d.y = d.depth * 180; });    // Update the nodes…   var node = vis.selectAll("g.node")       .data(nodes, function(d) { return d.id || (d.id = ++i); });    // Enter any new nodes at the parent's previous position.   var nodeEnter = node.enter().append("svg:g")       .attr("class", "node")       .attr("transform", function(d) { return "translate(" + source.y0 + "," + source.x0 + ")"; })       .on("click", function(d) { toggle(d); update(d); });    nodeEnter.append("svg:circle")       .attr("r", 1e-6)       .style("fill", function(d) { return d._children ? "lightsteelblue" : "#fff"; });    nodeEnter.append("svg:text")       .attr("x", function(d) { return d.children || d._children ? -10 : 10; })       .attr("dy", ".35em")       .attr("text-anchor", function(d) { return d.children || d._children ? "end" : "start"; })       .text(function(d) { return d.name; })       .style("fill-opacity", 1e-6);    // Transition nodes to their new position.   var nodeUpdate = node.transition()       .duration(duration)       .attr("transform", function(d) { return "translate(" + d.y + "," + d.x + ")"; });    nodeUpdate.select("circle")       .attr("r", 4.5)       .style("fill", function(d) { return d._children ? "lightsteelblue" : "#fff"; });    nodeUpdate.select("text")       .style("fill-opacity", 1);    // Transition exiting nodes to the parent's new position.   var nodeExit = node.exit().transition()       .duration(duration)       .attr("transform", function(d) { return "translate(" + source.y + "," + source.x + ")"; })       .remove();    nodeExit.select("circle")       .attr("r", 1e-6);    nodeExit.select("text")       .style("fill-opacity", 1e-6);    // Update the links…   var link = vis.selectAll("path.link")       .data(tree.links(nodes), function(d) { return d.target.id; });    // Enter any new links at the parent's previous position.   link.enter().insert("svg:path", "g")       .attr("class", "link")       .attr("d", function(d) {         var o = {x: source.x0, y: source.y0};         return diagonal({source: o, target: o});       })     .transition()       .duration(duration)       .attr("d", diagonal);    // Transition links to their new position.   link.transition()       .duration(duration)       .attr("d", diagonal);    // Transition exiting nodes to the parent's new position.   link.exit().transition()       .duration(duration)       .attr("d", function(d) {         var o = {x: source.x, y: source.y};         return diagonal({source: o, target: o});       })       .remove();    // Stash the old positions for transition.   nodes.forEach(function(d) {     d.x0 = d.x;     d.y0 = d.y;   }); }  // Toggle children. function toggle(d) {    // I could retrieve the child nodes here, but how to add them to the tree?    if (d.children) {     d._children = d.children;     d.children = null;   } else {     d.children = d._children;     d._children = null;   } } 

Answer 1

I was able to dynamically add nodes by adding the following code in the toggle function:

$.getJSON(addthese.json, function(addTheseJSON) {     var newnodes = tree.nodes(addTheseJSON.children).reverse();     d.children = newnodes[0];     update(d); }); 

Notes: I am using jQuery to retrieve the json file