tree of d3.js looks so crowd when too many data exist - d3.js

Question

i want to use d3.js to make data show in a tree. This is what I have done ,there is a problem that the svg will be so crowd when there are many data exist
Can you help me make it look better.
Here is my code
function update(source) {
// Compute the new tree layout.
var nodes = tree.nodes(root).reverse(), links = tree.links(nodes);
// Normalize for fixed-depth.
nodes.forEach(function(d) {
d.y = d.depth * 180;
});
// Update the nodes…
var node = svg.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("g").attr("class", "node")
.attr("transform", function(d) {
return "translate(" + source.y0 + "," + source.x0 + ")";
})
.on("click", click);
nodeEnter.append("circle")
.attr("r", 1e-6)
.style("fill", function(d) {
return d._children ? "lightsteelblue" : "#fff";
});
nodeEnter.append("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) {
if (d._children) {
return "lightsteelblue";
}
if (d.isHealth != undefined) {
return d.isHealth == false ? "red" : "green";
}
});
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 = svg.selectAll("path.link").data(links, function(d) {
return d.target.id;
});
// Enter any new links at the parent's previous position.
link.enter().insert("path", "g")
.attr("class", "link")
.attr("d", function(d) {
var o = {
x : source.x0,
y : source.y0
};
return diagonal({
source : o,
target : o
});
});
// 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;
});
}

Answer 1

I met the same problem. And I solved it by using nodeSize.
tree.nodeSize([x, y])
It will set separation between nodes. But this method will override the tree.size()
so you need to recount the coordinate about another nodes.
I hope my answer will help you.