Demo1

<!DOCTYPE html>
<html>
  <title>Demos</title>
  <meta charset="utf-8">
  <style>
    /* CSS part */
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
    h1 {
      color: #ffffff;
      font-family: 'Raleway';
      font-weight: normal;
      font-size: 1.75em;
      letter-spacing: .2em;
      line-height: 1.1em;
      margin:0px;
      text-align: center;
      text-transform: uppercase;
    }
    #container {
      width:800px;
    }
    #header {
      width:800px;
      height: 50px;
      padding: 5px;
      background: #1abc9c;
    }
    #sidebar {
      height:400px;
      width:140px;
      background: #1abc9c;
      float:left;
      font-family:  'Raleway';
      font-size: 11px;
      padding: 5px;
    }
    select, button {
      margin: 5px;
      font-family:  'Raleway'
      font-size: 20px;
    }
    #content {
      background-color:#ffffff;
      height:400px;
      width:650px;
      float:left;
    }
    #footer {
      width:800px;
      height: 50px;
      background: #1abc9c;
      float:left;
    }
    circle {
      stroke: #1abc9c;
      stroke-width: 2;
      fill: white;
    }
    .d3-tip {
      font-family: 'Raleway';
      line-height: 1;
      padding: 1px;
      background: transparent;
      color: #000;
      border-radius: 2px;
    }
    .axis path, .axis line {
      fill: none;
      stroke: grey;
      shape-rendering: crispEdges;
    }
    .axis text {
      font-family: 'Raleway';
      font-size: 11px;
    }
  </style>
  
  <body>
    <script src="https://d3js.org/d3.v3.min.js"></script>
    <script src="https://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js"></script>
    <div id = "container">
      <div id ="header">
        <h1>Demo Scatterplot</h1>
      </div>
    <div id ="sidebar">
      X-aixs:
      <select id="xAxisVar" onchange="reDraw()" >
        <option></option>
        <option value="physicalstrength" selected="selected">physical strength</option>
        <option value="fearfactor" >fear factor</option>
        <option value="killingpower">killing power</option>
        <option value="horrorrating">horror rating</option>
      </select>
      <br>
      Y-axis:
      <select id="yAxisVar" onchange="reDraw()">
        <option></option>
        <option value="physicalstrength">physical strength</option>
        <option value="fearfactor" selected="selected">fear factor</option>
        <option value="killingpower">killing power</option>
        <option value="horrorrating">horror rating</option>
      </select>
    </div>
    <div id ="content">
      <svg height="400" width="650">
      </svg>
      <script>
        
        // define data
        var horror = [{
        "name": "ape man",
        "physicalstrength": 20,
        "fearfactor": 7,
        "killingpower": 12,
        "horrorrating": 4,
        "cluster": 1
        }, {
        "name": "godzilla",
        "physicalstrength": 3,
        "fearfactor": 5,
        "killingpower": 4,
        "horrorrating": 8,
        "cluster": 2
        }, {
        "name": "the ghoul",
        "physicalstrength": 7,
        "fearfactor": 12,
        "killingpower": 2,
        "horrorrating": 7,
        "cluster": 1
        }, {
        "name": "the freak",
        "physicalstrength": 9,
        "fearfactor": 2,
        "killingpower": 1,
        "horrorrating": 17,
        "cluster": 1
        }, {
        "name": "dracula",
        "physicalstrength": 4,
        "fearfactor": 17,
        "killingpower": 5,
        "horrorrating": 16,
        "cluster": 2
        }, {
        "name": "the hangman",
        "physicalstrength": 2,
        "fearfactor": 4,
        "killingpower": 13,
        "horrorrating": 8,
        "cluster": 2
        }, {
        "name": "incredible melting man",
        "physicalstrength": 3,
        "fearfactor": 8,
        "killingpower": 15,
        "horrorrating": 6,
        "cluster": 1
        }, {
        "name": "the thing",
        "physicalstrength": 19,
        "fearfactor": 4,
        "killingpower": 11,
        "horrorrating": 7,
        "cluster": 1
        }];

// set constants
        var w = 420,
            h = 400,
            padding = 30;
        
        // create adaptable scales
        var xScale = d3.scale.linear()
                       .domain([0, d3.max(horror, function(d) { return d3.max([d.physicalstrength, d.fearfactor, d.killingpower, d.horrorrating]); })])
                       .range([padding, w - padding]);
        var yScale = d3.scale.linear()
                       .domain([0, d3.max(horror, function(d) { return d3.max([d.physicalstrength, d.fearfactor, d.killingpower, d.horrorrating]); })])
                       .range([h - padding, padding]);
                       // notice it is from large to small because its origin is in top left corner
      
        // select the svg
        var svg = d3.select("svg");
        
        // define the tooltip
        var tip = d3.tip()
                    .attr("class", "d3.tip")
                    .offset([-10, 0])
                    .html(function(d) { return d.name; });
        
        // define elements in the svg
        var diag_circles = svg.selectAll("circle")
                              .data(horror)
                              .enter()
                              .append("circle")
                              .attr("cx", function(d) { return xScale(d.physicalstrength); })
                              .attr("cy", function(d) { return yScale(d.fearfactor); })
                              .attr("r", 10)
                              .style("stroke", function(d) {
                                if (d.cluster === 1) { return "#1abc9c"; }
                                else { return "gray"; }
                              })
                              .call(tip)
                              .on("mouseover", tip.show)
                              .on("mouseout", tip.hide);
                
        // set up the axes
        var xAxis = d3.svg.axis()
                      .scale(xScale)
                      .orient("bottom");
        var yAxis = d3.svg.axis()
                      .scale(yScale)
                      .orient("left");
        
        // add the axes to svg
        svg.append("g")
           .attr("class", "axis")
           .attr("transform", "translate(0, " + (h - padding) + ")")
           .call(xAxis);
        svg.append("g")
           .attr("class", "axis")
           .attr("transform", "translate(" + padding + ", 0)")
           .call(yAxis);
  
        function reDraw() {
          xVar = document.getElementById('xAxisVar').value;
          yVar = document.getElementById('yAxisVar').value;
          d3.selectAll("circle")
            .transition()
            .duration(1000)
            .attr("cx", function (d) {
              return eval("xScale(d." + xVar + ");");
            })
            .attr("cy", function (d) {
              return eval("yScale(d." + yVar + ");");
            })
            .attr("opacity", 0.5);
        }  
        
      </script>
    </div>
    <div id ="footer">
    </div>
  </div>
  </body>
</html>

Modified http://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js to a secure url

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

https://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js