点击D3树节点

我目前有一个D3树布局的节点，可以在运行时添加文本附加到每个节点。几乎所有的工作都很好，除了node.on(..)函数，比如node.on("mousedown" ....)。问题是节点本身不响应单击，而附加的文本响应。即node.on("mousedown",...)被触发时，附加的文本被点击，而不是实际的节点。任何指导将非常感激!核心函数的代码如下所示，它只接受一个JSON样式的对象和一个父对象id，然后将该JSON数据作为给定父对象的子对象插入到树中:

function update(record_to_add, parent) {
    if (nodes.length >= 500) return clearInterval(timer);
    // Add a new node to a random parent.
    var n = {id: nodes.length, Username: record_to_add.Username},
            p = nodes[parent];
    if (p.children) p.children.push(n); else p.children = [n];
    nodes.push(n);
    // Recompute the layout and data join.
    node = node.data(tree.nodes(root), function(d) { return d.id; });
    link = link.data(tree.links(nodes), function(d) { return d.source.id + "-" + d.target.id; });
    // Add entering nodes in the parent’s old position.
    node.enter().append("circle", "g")
            .attr("class", "node")
            .attr("r", 10)
            .attr("cx", function(d) { return d.parent.px; })
            .attr("cy", function(d) { return d.parent.py; });
    // Add entering links in the parent’s old position.
    link.enter().insert("path", ".node")
            .attr("class", "link")
            .attr("d", function(d) {
                var o = {x: d.source.px, y: d.source.py};
                return diagonal({source: o, target: o});
            });
    node.enter().insert("text")
            .attr("x", function(d) { return (d.parent.px);})
            .attr("y", function(d) { return (d.parent.py);})
            .text(function(d) { return d.Username; });
    node.on("mousedown", function (d) {
        var g = d3.select(this); // The node
        // The class is used to remove the additional text later
        console.log("FOO");
    });
    node.on("mouseover", function (d) {
        var g = d3.select(this); // The node
        // The class is used to remove the additional text later
        var info = g.append('text')
                .classed('info', true)
                .attr('x', 20)
                .attr('y', 10)
                .text('More info');
    });
    // Transition nodes and links to their new positions.
    var t = svg.transition()
            .duration(duration);
    t.selectAll(".link")
            .attr("d", diagonal);
    t.selectAll(".node")
            .attr("cx", function(d) { return d.px = d.x; })
            .attr("cy", function(d) { return d.py = d.y; });
    t.selectAll("text")
            .style("fill-opacity", 1)
            .attr("x", function(d) { return d.px = d.x; })
            .attr("y", function(d) { return d.py = d.y; });
}