To load a json file, you can create a function like this:
var loadJson = function(jsonFile) {
d3.json(jsonFile, function(error, data) {
if (error) return console.error(error);
svg.selectAll("circle").remove();
svg.selectAll("text").remove();
var focus = data,
nodes = pack.nodes(data),
view;
var circle = svg.selectAll("circle")
.data(nodes)
.enter().append("circle")
.attr("class", function(d) { return d.parent ? d.children ? "node" : "node node--leaf" : "node node--root"; })
.style("fill", function(d) { return d.children ? color(d.depth) : null; })
.on("click", function(d) { if (focus !== d) zoom(d), d3.event.stopPropagation(); });
var text = svg.selectAll("text")
.data(nodes)
.enter().append("text")
.attr("class", "label")
.style("fill-opacity", function(d) { return d.parent === data ? 1 : 0; })
.style("display", function(d) { return d.parent === data ? null : "none"; })
.text(function(d) { return d.name; });
var node = svg.selectAll("circle,text");
d3.select("body")
.style("background", color(-1))
.on("click", function() { zoom(data); });
zoomTo([data.x, data.y, data.r * 2 + margin]);
function zoom(d) {
var focus0 = focus; focus = d;
var transition = d3.transition()
.duration(d3.event.altKey ? 7500 : 750)
.tween("zoom", function(d) {
var i = d3.interpolateZoom(view, [focus.x, focus.y, focus.r * 2 + margin]);
return function(t) { zoomTo(i(t)); };
});
transition.selectAll("text")
.filter(function(d) { return d.parent === focus || this.style.display === "inline"; })
.style("fill-opacity", function(d) { return d.parent === focus ? 1 : 0; })
.each("start", function(d) { if (d.parent === focus) this.style.display = "inline"; })
.each("end", function(d) { if (d.parent !== focus) this.style.display = "none"; });
}
function zoomTo(v) {
var k = diameter / v[2]; view = v;
node.attr("transform", function(d) { return "translate(" + (d.x - v[0]) * k + "," + (d.y - v[1]) * k + ")"; });
circle.attr("r", function(d) { return d.r * k; });
}
});
};
... and then call it using loadJson("flare.json");
Here's an example with multiple json files in action - http://bl.ocks.org/chule/74e95deeadd353e42034