I am doing force layout, on event click i add new node and connect by line. But line overlaps node. Why? My code is shown http://jsfiddle.net/WRGtL/
function click(d) {
if (d3.event.defaultPrevented) return; // ignore drag
//alert("clicked");
var d = {id:"d"};
nodes.push(nodeId[index]);
if(index==0)
links.push({source: a, target: nodeId[index]});
else
links.push({source: nodes[1], target: nodeId[index]});
index++;
start();
}