d3: Optionally add child elements based on node content in force layout

问题

Using the force layout in d3, I can happily add nodes as, say, an SVG group of a circle and some text:

var node = vis.selectAll(".node")
    .data(nodes)
    .enter().append("svg:g")
    .attr("class", "node");
node.append("svg:circle")
    .attr("r", 5);
node.append("svg:text")
    .text(function(d) { return d.nodetext });

However, I would like to optionally add another element to the group, dependent on the node data: so if the data for this node contains an "image" attribute, I'd like to add a new child-element (an svg:image). It's easy to add the svg:image to all nodes (I just do it as I've done the circle and text above). It's also easy to dynamically change an attribute of an element you've already created (by having a function as the attribute's value, as per text above). I do not know how to add an svg:image child element only if the data contains an image attribute. What's the best way of achieving this?

回答1:

Try selection.filter:

node.filter(function(d) { return d.image; }).append("image")
    .attr("xlink:href", function(d) { return d.image; })
    .attr("width", 16)
    .attr("height", 16);

来源：https://stackoverflow.com/questions/12787769/d3-optionally-add-child-elements-based-on-node-content-in-force-layout