Modify lines/tooltip on hover

http://stackoverflow.com/questions/26790124/modify-lines-tooltip-on-hover

by Mark

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>
<div id="tooltip" style="display:none"></div>

CSS

.node {
    cursor: pointer;
}
.node circle {
    fill: #fff;
    stroke: steelblue;
    stroke-width: 1.5px;
}
.node text {
    font: 10px sans-serif;
}
.link {
    fill: none;
    stroke: #ccc;
    stroke-width: 1.5px;
}
.link:hover {
    stroke:#5D8AFF;
    stroke-width: 4px;
}

div#tooltip{
    color:#ffffff;
    background:#000000;
    opacity:1;
    padding:5px;
}

JavaScript

var margin = {
    top: 20,
    right: 120,
    bottom: 20,
    left: 120
},
width = 480 - margin.right - margin.left,
    height = 400 - margin.top - margin.bottom;

var i = 0,
    duration = 750,
    root;

var tree = d3.layout.tree()
    .size([height, width]);

var diagonal = d3.svg.diagonal()
    .projection(function (d) {
    return [d.y, d.x];
});

var svg = d3.select("body").append("svg")
    .attr("width", width + margin.right + margin.left)
    .attr("height", height + margin.top + margin.bottom)
    .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");


var root = { //json var root
    "name": "flare",
        "test": "blue",
        "children": [{
        "name": "analytics",
            "test": "red",
            "children": [{
            "name": "cluster",
                "test": "green",
                "children": [{
                "name": "AgglomerativeCluster",
                    "test": "blue",
                    "size": 3938
            }, {
                "name": "CommunityStructure",
                    "test": "yellow",
                    "size": 3812
            }, {
                "name": "HierarchicalCluster",
                    "test": "orange",
                    "size": 6714
            }, {
                "name": "MergeEdge",
                    "test": "someColor",
                    "size": 743
            }]
        }, {
            "name": "graph",
                "test": "someColor",
                "children": [{
                "name": "BetweennessCentrality",
                    "test": "someColor",
                    "size": 3534
            }, {
                "name": "LinkDistance",
                    "test": "someColor",
                    "size": 5731
            }, {
                "name": "MaxFlowMinCut",
                    "size": 7840
            }, {
                "name": "ShortestPaths",
                    "test": "someColor",
                    "size":...