Adding Dynamic content to d3.js tree on click of child node : http://bl.ocks.org/d3noob/8375092

d3treeAddDynamicChild.js

function click(d) {
        if (!d.children && !d._children)
        {
            d3.json("http://xxxx:2222/getChildNodes", function(error,response) {
                response.children.forEach(function(child){
                      if (!tree.nodes(d)[0]._children){
                          tree.nodes(d)[0]._children = [];
                      }
                      child.x = d.x0;
                      child.y = d.y0;
                      tree.nodes(d)[0]._children.push(child);
                });
                if (d.children) {
                     d._children = d.children;
                     d.children = null;
                }
                else {
                    d.children = d._children;
                    d._children = null;
                }
                update(d);
            });
        }
        if (d.children) {
            d._children = d.children;
            d.children = null;
        }
        else {
            d.children = d._children;
            d._children = null;
        }
        update(d);
    }