Add and remove nodes

Click to add nodes! Nodes near the cursor will be linked to the new node. Clicking an existing node will remove it.

This is an extension of this example, adding the capability of removing nodes by clicking them. This means that dragging is no longer supported.

forked from tgk's block: Add and remove nodes

<!DOCTYPE html>
<meta charset="utf-8">
<style>

rect {
  fill: none;
  pointer-events: all;
}

.node {
  fill: #000;
}

.cursor {
  fill: none;
  stroke: brown;
  pointer-events: none;
}

.link {
  stroke: #999;
}

</style>
<body>
<script src="https://d3js.org/d3.v3.min.js"></script>
<script>

var width = 960,
    height = 500;

var fill = d3.scale.category20();

var force = d3.layout.force()
    .size([width, height])
    .nodes([{}]) // initialize with a single node
    .linkDistance(30)
    .charge(-60)
    .on("tick", tick);

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height)
    .on("mousemove", mousemove)
    .on("mousedown", mousedownCanvas);

svg.append("rect")
    .attr("width", width)
    .attr("height", height);

var nodes = force.nodes(),
    links = force.links(),
    node = svg.selectAll(".node"),
    link = svg.selectAll(".link");

var cursor = svg.append("circle")
    .attr("r", 30)
    .attr("transform", "translate(-100,-100)")
    .attr("class", "cursor");

restart();

function mousemove() {
  cursor.attr("transform", "translate(" + d3.mouse(this) + ")");
}

function mousedownCanvas() {
  var point = d3.mouse(this),
      node = {x: point[0], y: point[1]},
      n = nodes.push(node);

// add links to any nearby nodes
  nodes.forEach(function(target) {
    var x = target.x - node.x,
        y = target.y - node.y;
    if (Math.sqrt(x * x + y * y) < 30) {
      links.push({source: node, target: target});
    }
  });

restart();
}

function mousedownNode(d, i) {
  nodes.splice(i, 1);
  links = links.filter(function(l) {
    return l.source !== d && l.target !== d;
  });
  d3.event.stopPropagation();

restart();
}

node.attr("cx", function(d) { return d.x; })
      .attr("cy", function(d) { return d.y; });
}

function restart() {
  node = node.data(nodes);

node.enter().insert("circle", ".cursor")
      .attr("class", "node")
      .attr("r", 5)
      .on("mousedown", mousedownNode);

node.exit()
      .remove();

link = link.data(links);

link.enter().insert("line", ".node")
      .attr("class", "link");
  link.exit()
      .remove();

force.start();
}

</script>

Modified http://d3js.org/d3.v3.min.js to a secure url

https://d3js.org/d3.v3.min.js