d3.js

function d3Graph(nodes, links) {
    var width = 1000,
        height = 800;
    
    var force = d3.layout.force()
        .nodes(d3.values(nodes))
        .links(links)
        .size([width, height])
        .linkDistance(150)
        .charge(-300)
        .on("tick", tick)
        .start();
    
    var svg = d3.select("#drawarea").append("svg")
        .attr("width", width)
        .attr("height", height);
    
    // Per-type markers, as they don't inherit styles.
    svg.append("defs").selectAll("marker")
        .data(['1', '2', "3"])
        .enter().append("marker")
        .attr("id", function(d) { return d; })
        .attr("viewBox", "0 -5 10 10")
        .attr("refX", 15)
        .attr("refY", -1.5)
        .attr("markerWidth", 6)
        .attr("markerHeight", 6)
        .attr("orient", "auto")
        .append("path")
        .attr("d", "M0,-5L10,0L0,5");
    
    var path = svg.append("g").selectAll("path")
        .data(force.links())
        .enter().append("path")
        .attr("class", function(d) { return "link " + d.type; })
        .attr("marker-end", function(d) { return "url(#" + d.type + ")"; });
    
    var circle = svg.append("g").selectAll("circle")
        .data(force.nodes())
        .enter().append("circle")
        .attr("r", 6)
        .call(force.drag);
    
    var text = svg.append("g").selectAll("text")
        .data(force.nodes())
        .enter().append("text")
        .attr("x", 8)
        .attr("y", ".31em")
        .text(function(d) { return d.name; });
    
    // Use elliptical arc path segments to doubly-encode directionality.
    function tick() {
      path.attr("d", linkArc);
      circle.attr("transform", transform);
      text.attr("transform", transform);
    }
    
    function linkArc(d) {
      var dx = d.target.x - d.source.x,
          dy = d.target.y - d.source.y,
          dr = Math.sqrt(dx * dx + dy * dy);
      return "M" + d.source.x + "," + d.source.y + "A" + dr + "," + dr + " 0 0,1 " + d.target.x + "," + d.target.y;
    }
    
    function transform(d) {
      return "translate(" + d.x + "," + d.y + ")";
    }
}