https://preview.c9users.io/quixomatic/rainking-fun-view/index.html

dndTree.js

buildJson(function (data) {

    // Calculate total nodes, max label length
    var totalNodes = 0;
    var maxLabelLength = 0;
    // variables for drag/drop
    var selectedNode = null;
    var draggingNode = null;
    // panning variables
    var panSpeed = 200;
    var panBoundary = 20; // Within 20px from edges will pan when dragging.
    // Misc. variables
    var i = 0;
    var duration = 750;
    var root;

    // size of the diagram
    var viewerWidth = $(document).width();
    var viewerHeight = $(document).height();

    var tree = d3.layout.tree()
        .size([viewerHeight, viewerWidth]);

    // define a d3 diagonal projection for use by the node paths later on.
    var diagonal = d3.svg.diagonal()
        .projection(function(d) {
            return [d.y, d.x];
        });

    // A recursive helper function for performing some setup by walking through all nodes

    function visit(parent, visitFn, childrenFn) {
        if (!parent) return;

        visitFn(parent);

        var children = childrenFn(parent);
        if (children) {
            var count = children.length;
            for (var i = 0; i < count; i++) {
                visit(children[i], visitFn, childrenFn);
            }
        }
    }

    // Call visit function to establish maxLabelLength
    visit(data, function(d) {
        totalNodes++;
        maxLabelLength = Math.max(d.name.length, maxLabelLength);

    }, function(d) {
        return d.children && d.children.length > 0 ? d.children : null;
    });


    // sort the tree according to the node names

    function sortTree() {
        tree.sort(function(a, b) {
            return b.name.toLowerCase() < a.name.toLowerCase() ? 1 : -1;
        });
    }
    // Sort the tree initially incase the JSON isn't in a sorted order.
    sortTree();

    // TODO: Pan function, can be better implemented.

    function pan(domNode, direction) {
        var speed = panSpeed;
        if (panTimer) {
            clearTimeout(panTimer);
            translateCoords = d3.transform(svgGroup.attr("transform"));
            if (direction == 'left' || direction == 'right') {
                translateX = direction == 'left' ? translateCoords.translate[0] + speed : translateCoords.translate[0] - speed;
                translateY = translateCoords.translate[1];
            } else if (direction == 'up' || direction == 'down') {
                translateX = translateCoords.translate[0];
                translateY = direction == 'up' ? translateCoords.translate[1] + speed : translateCoords.translate[1] - speed;
            }
            scaleX = translateCoords.scale[0];
            scaleY = translateCoords.scale[1];
            scale = zoomListener.scale();
            svgGroup.transition().attr("transform", "translate(" + translateX + "," + translateY + ")scale(" + scale + ")");
            d3.select(domNode).select('g.node').attr("transform", "translate(" + translateX + "," + translateY + ")");
            zoomListener.scale(zoomListener.scale());
            zoomListener.translate([translateX, translateY]);
            panTimer = setTimeout(function() {
                pan(domNode, speed, direction);
            }, 50);
        }
    }

    // Define the zoom function for the zoomable tree

    function zoom() {
        svgGroup.attr("transform", "translate(" + d3.event.translate + ")scale(" + d3.event.scale + ")");
    }


    // define the zoomListener which calls the zoom function on the "zoom" event constrained within the scaleExtents
    var zoomListener = d3.behavior.zoom().scaleExtent([0.1, 3]).on("zoom", zoom);

    function initiateDrag(d, domNode) {
        draggingNode = d;
        d3.select(domNode).select('.ghostCircle').attr('pointer-events', 'none');
        d3.selectAll('.ghostCircle').attr('class', 'ghostCircle show');
        d3.select(domNode).attr('class', 'node activeDrag');

        svgGroup.selectAll("g.node").sort(function(a, b) { // select the parent and sort the path's
            if (a.id != draggingNode.id) return 1; // a is not the hovered element, send "a" to the back
            else return -1; // a is the hovered element, bring "a" to the front
        });
        // if nodes has children, remove the links and nodes
        if (nodes.length > 1) {
            // remove link paths
            links = tree.links(nodes);
            nodePaths = svgGroup.selectAll("path.link")
                .data(links, function(d) {
                    return d.target.id;
                }).remove();
            // remove child nodes
            nodesExit = svgGroup.selectAll("g.node")
                .data(nodes, function(d) {
                    return d.id;
                }).filter(function(d, i) {
                    if (d.id == draggingNode.id) {
                        return false;
                    }
                    return true;
                }).remove();
        }

        // remove parent link
        parentLink = tree.links(tree.nodes(draggingNode.parent));
        svgGroup.selectAll('path.link').filter(function(d, i) {
            if (d.target.id == draggingNode.id) {
                return true;
            }
            return false;
        }).remove();

        dragStarted = null;
    }

    // define the baseSvg, attaching a class for styling and the zoomListener
    var baseSvg = d3.select("#tree-container").append("svg")
        .attr("width", viewerWidth)
        .attr("height", viewerHeight)
        .attr("class", "overlay")
        .call(zoomListener);


    // Define the drag listeners for drag/drop behaviour of nodes.
    dragListener = d3.behavior.drag()
        .on("dragstart", function(d) {
            if (d == root) {
                return;
            }
            dragStarted = true;
            nodes = tree.nodes(d);
            d3.event.sourceEvent.stopPropagation();
            // it's important that we suppress the mouseover event on the node being dragged. Otherwise it will absorb the mouseover event and the underlying node will not detect it d3.select(this).attr('pointer-events', 'none');
        })
        .on("drag", function(d) {
            if (d == root) {
                return;
            }
            if (dragStarted) {
                domNode = this;
                initiateDrag(d, domNode);
            }

            // get coords of mouseEvent relative to svg container to allow for panning
            relCoords = d3.mouse($('svg').get(0));
            if (relCoords[0] < panBoundary) {
                panTimer = true;
                pan(this, 'left');
            } else if (relCoords[0] > ($('svg').width() - panBoundary)) {

                panTimer = true;
                pan(this, 'right');
            } else if (relCoords[1] < panBoundary) {
                panTimer = true;
                pan(this, 'up');
            } else if (relCoords[1] > ($('svg').height() - panBoundary)) {
                panTimer = true;
                pan(this, 'down');
            } else {
                try {
                    clearTimeout(panTimer);
                } catch (e) {

                }
            }

            d.x0 += d3.event.dy;
            d.y0 += d3.event.dx;
            var node = d3.select(this);
            node.attr("transform", "translate(" + d.y0 + "," + d.x0 + ")");
            updateTempConnector();
        }).on("dragend", function(d) {
            if (d == root) {
                return;
            }
            domNode = this;
            if (selectedNode) {
                // now remove the element from the parent, and insert it into the new elements children
                var index = draggingNode.parent.children.indexOf(draggingNode);
                if (index > -1) {
                    draggingNode.parent.children.splice(index, 1);
                }
                if (typeof selectedNode.children !== 'undefined' || typeof selectedNode._children !== 'undefined') {
                    if (typeof selectedNode.children !== 'undefined') {
                        selectedNode.children.push(draggingNode);
                    } else {
                        selectedNode._children.push(draggingNode);
                    }
                } else {
                    selectedNode.children = [];
                    selectedNode.children.push(draggingNode);
                }
                // Make sure that the node being added to is expanded so user can see added node is correctly moved
                expand(selectedNode);
                sortTree();
                endDrag();
            } else {
                endDrag();
            }
        });

    function endDrag() {
        selectedNode = null;
        d3.selectAll('.ghostCircle').attr('class', 'ghostCircle');
        d3.select(domNode).attr('class', 'node');
        // now restore the mouseover event or we won't be able to drag a 2nd time
        d3.select(domNode).select('.ghostCircle').attr('pointer-events', '');
        updateTempConnector();
        if (draggingNode !== null) {
            update(root);
            centerNode(draggingNode);
            draggingNode = null;
        }
    }

    // Helper functions for collapsing and expanding nodes.

    function collapse(d) {
        if (d.children) {
            d._children = d.children;
            d._children.forEach(collapse);
            d.children = null;
        }
    }

    function expand(d) {
        if (d._children) {
            d.children = d._children;
            d.children.forEach(expand);
            d._children = null;
        }
    }

    var overCircle = function(d) {
        selectedNode = d;
        updateTempConnector();
    };
    var outCircle = function(d) {
        selectedNode = null;
        updateTempConnector();
    };

    // Function to update the temporary connector indicating dragging affiliation
    var updateTempConnector = function() {
        var data = [];
        if (draggingNode !== null && selectedNode !== null) {
            // have to flip the source coordinates since we did this for the existing connectors on the original tree
            data = [{
                source: {
                    x: selectedNode.y0,
                    y: selectedNode.x0
                },
                target: {
                    x: draggingNode.y0,
                    y: draggingNode.x0
                }
            }];
        }
        var link = svgGroup.selectAll(".templink").data(data);

        link.enter().append("path")
            .attr("class", "templink")
            .attr("d", d3.svg.diagonal())
            .attr('pointer-events', 'none');

        link.attr("d", d3.svg.diagonal());

        link.exit().remove();
    };

    // Function to center node when clicked/dropped so node doesn't get lost when collapsing/moving with large amount of children.

    function centerNode(source) {
        scale = zoomListener.scale();
        x = -source.y0;
        y = -source.x0;
        x = x * scale + viewerWidth / 2;
        y = y * scale + viewerHeight / 2;
        d3.select('g').transition()
            .duration(duration)
            .attr("transform", "translate(" + x + "," + y + ")scale(" + scale + ")");
        zoomListener.scale(scale);
        zoomListener.translate([x, y]);
    }

    // Toggle children function

    function toggleChildren(d) {
        if (d.children) {
            d._children = d.children;
            d.children = null;
        } else if (d._children) {
            d.children = d._children;
            d._children = null;
        }
        if (d.parent) {
            if (typeof d.parent.children != 'undefined') {
                d.parent.children.forEach(function(element) {
                    if (d !== element) {
                        collapse(element);
                    }
                });
            }
        }
        return d;
    }

    // Toggle children on click.

    function click(d) {
        if (d3.event.defaultPrevented) return; // click suppressed
        d = toggleChildren(d);
        update(d);
        centerNode(d);
    }
    
    function toggleAll(d) {
        if (d.children) {
            d.children.forEach(toggleAll);
            toggleChildren(d);
        }
    }

    function update(source) {
        // Compute the new height, function counts total children of root node and sets tree height accordingly.
        // This prevents the layout looking squashed when new nodes are made visible or looking sparse when nodes are removed
        // This makes the layout more consistent.
        var levelWidth = [1];
        var childCount = function(level, n) {

            if (n.children && n.children.length > 0) {
                if (levelWidth.length <= level + 1) levelWidth.push(0);

                levelWidth[level + 1] += n.children.length;
                n.children.forEach(function(d) {
                    childCount(level + 1, d);
                });
            }
        };
        childCount(0, root);
        var newHeight = d3.max(levelWidth) * 50; // 25 pixels per line  
        tree = tree.size([newHeight, viewerWidth]);

        // Compute the new tree layout.
        var nodes = tree.nodes(root).reverse(),
            links = tree.links(nodes);

        // Set widths between levels based on maxLabelLength.
        nodes.forEach(function(d) {
            d.y = ((d.depth - 1) * (maxLabelLength * 5)); //maxLabelLength * 10px
            // alternatively to keep a fixed scale one can set a fixed depth per level
            // Normalize for fixed-depth by commenting out below line
            // d.y = (d.depth * 500); //500px per level.
        });

        // Update the nodes…
        node = svgGroup.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")
            .call(dragListener)
            .attr("class", "node")
            .attr("transform", function(d) {
                return "translate(" + source.y0 + "," + source.x0 + ")";
            })
            .on('click', click);
        
        
        
        
        nodeEnter.append("rect")
            .attr('class', 'node-container-2')
            .attr('rx', '3')
            .attr('ry', '3')
            .attr("x", -198)
            .attr("y", -15)
            .attr("width", function (d) {
                return d.children || d._children ? 200 : 0;
            })
            .attr("height", function (d) {
                return d.children || d._children ? 30 : 0;
            })
            .attr("stroke", function (d) {
                if (d.depth < 2) {
                    return '#faa934'
                } else {
                    console.log(d)
                    return '#acd2d3'
                }
            })
            .attr("stroke-width", 1)
            .style("fill", function (d) {
                if (d.depth < 2) {
                    return '#faa934'
                } else {
                    console.log(d)
                    return '#acd2d3'
                }
                // return d._children ? "#faa934" : "#faa934";
            })
                
        nodeEnter.append("rect")
            .attr('class', 'node-container-1')
            .attr("x", -198)
            .attr("y", -15)
            .attr("width", function (d) {
                return d.children || d._children ? 196 : 0;
            })
            .attr("height", function (d) {
                return d.children || d._children ? 30 : 0;
            })
            .attr("stroke", function (d) {
                return d.children || d._children ? '#d6dde4' : 'none';
            })
            .attr("stroke-width", 1)
            .style("fill", function (d) {
                return d._children ? "#fff" : "#fff";
            })
            
        nodeEnter.append("rect")
            .attr('class', 'node-container-strokefix')
            .attr("x", -3)
            .attr("y", -14)
            .attr("width", function (d) {
                return d.children || d._children ? 1 : 0;
            })
            .attr("height", function (d) {
                return d.children || d._children ? 28 : 0;
            })
            .attr("stroke", function (d) {
                return d.children || d._children ? '#fff' : 'none';
            })
            .attr("stroke-width", 1)
            .style("fill", function (d) {
                return d._children ? "#fff" : "#fff";
            })

        nodeEnter.append("text")
            .attr("x", function(d) {
                return d.children || d._children ? -10 : 10;
            })
            .attr("dy", ".35em")
            .attr('class', 'nodeText')
            .attr("text-anchor", function(d) {
                return d.children || d._children ? "end" : "start";
            })
            .text(function(d) {
                return d.name;
            })
            .style("fill-opacity", 0);
            
        nodeEnter.append("circle")
            .attr('class', 'nodeCircle')
            .attr("r", 0)
            .attr("stroke", function (d) {
                if (d.depth < 2) {
                    return '#faa934'
                } else if (d.depth < 3) {
                    return '#acd2d3'
                } else {
                    return '#c0d4ae'
                }
            })
            .style("fill", function(d) {
                if (d.depth < 2) {
                    return '#fdddb0'
                } else {
                    return '#d7e9ea'
                }
            });

        // phantom node to give us mouseover in a radius around it
        nodeEnter.append("circle")
            .attr('class', 'ghostCircle')
            .attr("r", 30)
            .attr("opacity", 0.2) // change this to zero to hide the target area
        .style("fill", "red")
            .attr('pointer-events', 'mouseover')
            .on("mouseover", function(node) {
                overCircle(node);
            })
            .on("mouseout", function(node) {
                outCircle(node);
            });

        // Update the text to reflect whether node has children or not.
        node.select('text')
            .attr("x", function(d) {
                return d.children || d._children ? -10 : 10;
            })
            .attr("text-anchor", function(d) {
                return d.children || d._children ? "end" : "start";
            })
            .attr('class', 'node-text')
            .text(function(d) {
                return d.name;
            });
            
        d3.selectAll('.node').each(function () {
            var textWidth = d3.select(this).select('.node-text').style('width').replace('px','')
            textWidth = parseInt(textWidth) + 20
            d3.select(this).select('.node-container-1')
                .attr('x', (textWidth + 2) * -1)
                .style('width', textWidth + 'px')
            d3.select(this).select('.node-container-2')
                .attr('x', (textWidth - 2) * -1)
                .style('width', textWidth + 'px')
        })

        // Change the circle fill depending on whether it has children and is collapsed
        node.select("circle.nodeCircle")
            .attr("r", 4.5)
            .style("fill", function(d) {
                if (d._children) {
                    if (d.depth < 2) {
                        return '#fdddb0'
                    } else {
                        return '#d7e9ea'
                    }
                } else {
                    return '#fff'
                }
            });

        // Transition nodes to their new position.
        var nodeUpdate = node.transition()
            .duration(duration)
            .attr("transform", function(d) {
                return "translate(" + d.y + "," + d.x + ")";
            });

        // Fade the text in
        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", 0);

        nodeExit.select("text")
            .style("fill-opacity", 0);

        // Update the links…
        var link = svgGroup.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();
            
        link.attr('stroke', function(d) {
            console.log(d)
            if (d.target.depth == 2) {
                return '#faa934'
            } 
            
            if (d.target.depth == 3) {
                return '#acd2d3'
            }
        });

        // Stash the old positions for transition.
        nodes.forEach(function(d) {
            d.x0 = d.x;
            d.y0 = d.y;
        });
        
        // +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
        // Remove Root Node, ultra mega important!!!
        // +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
        node.each(function(d){
            if (d.name == "flare") 
                d3.select(this).remove();});
        link.each(function(d){
            if (d.source.name == "flare") 
                d3.select(this).remove();});
    }

    // Append a group which holds all nodes and which the zoom Listener can act upon.
    var svgGroup = baseSvg.append("g");

    // Define the root
    root = data;
    root.x0 = viewerHeight / 2;
    root.y0 = 0;
    
    // Start all nodes closed
    root.children.forEach(toggleAll);

    // Layout the tree initially and center on the root node.
    update(root);
    centerNode(root);
});

// Get Data and format it properly for presentation
function getJsonData (pathToData, callback) {
    $.getJSON( pathToData, function() {
        console.log( "Retrieving: " + pathToData );
    }).done(function(data) {
        callback({
            error: false,
            data: data
        });
    })
    .fail(function() {
        callback({
            error: true
        });
    });
}

function buildJson (builder) {
    var runOnce = true, categories_raw, technologies_raw, formatted_json = {
        'name' : 'flare', 
        'children' : []
    }
    
    //+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    // First get all of the categories and subcategories
    //+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    getJsonData('assets/json/categories.json', function (data) {
        if (!data.error) {
            //+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
            // Categories and Subcategories Retreived now build it out
            //+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
            categories_raw = data.data
            
            //+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
            // Technologies retreived now build it out
            //+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
            getJsonData('assets/json/technologies.json', function (data) {
                if (!data.error) {
                    technologies_raw = data.data
                    
                    var categories = categories_raw[0], subcategories = categories_raw[1], technologies = technologies_raw, formatted_categories = [], formatted_subcategories = [], formatted_technologies = []
                    
                    subcategories.forEach ( function (value, index) {
                        formatted_subcategories.push({
                            'name' : value.label,
                            'id' : value.id,
                            'children' : [],
                            'parent' : value.parent
                        })
                    })
                    
                    technologies.forEach ( function (value, index) {
                        var result = formatted_subcategories.filter(function( obj ) {
                            return obj.id == value.subCat;
                        });
                        
                        if (typeof result[0] != 'undefined') {
                            result[0].children.push({
                                'name' : value.label
                            })
                        }
                    })
                    
                    categories.forEach ( function (value, index) {
                        var result = formatted_subcategories.filter(function( obj ) {
                            return obj.parent == value.id;
                        });
                        
                        formatted_json.children.push({
                            'name' : value.label,
                            'id' : value.id,
                            'children' : result
                        })
                    })
                    
                    builder(formatted_json)
                }
            })
        }
    })
}

index.html

<!DOCTYPE html>
<meta charset="utf-8">
<style type="text/css">
  
	.node {
    cursor: pointer;
  }

  .overlay{
      background-color:#EEE;
  }
   
  .node circle {
    fill: #fff;
    stroke-width: 1.5px;
  }
   
  .node text {
    font-size:10px; 
    font-family:sans-serif;
  }
   
  .link {
    fill: none;
    stroke-width: 1.5px;
  }

  .templink {
    fill: none;
    stroke: red;
    stroke-width: 3px;
  }

  .ghostCircle.show{
      display:block;
  }

  .ghostCircle, .activeDrag .ghostCircle{
       display: none;
  }

</style>
<script src="//code.jquery.com/jquery-1.10.2.min.js"></script>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="assets/js/dndTree.js"></script>
<body>
    <div id="tree-container"></div>
</body>
</html>