Plotly text hover

HTML

<script src="https://cdn.plot.ly/plotly-latest.min.js"></script>
<script src="https://github.com/mbostock/d3/raw/v1.10.1/d3.js"></script>
<div id="graph"></div>

JavaScript

var zData = createData();
var xData = d3.range(0, zData.length);
var yData = d3.range(0, zData[0].length);

var data = [ {
  z: zData,
  x: xData,
  y: yData,
  type: 'contour',  
  colorscale: 'Jet',
  showscale: false,
  autocontour: false,  
  contours: {
    start: -5,
    end: 3,
    size: 0.5
  }
}];

var layout = {
margin: {
b: 0,
l: 0,
r: 0,
t: 0
},
height: 600,
width: 600,
  title: '',
  xaxis: {
  		ticks: '',
      showticklabels: false  
     
  },
  yaxis: {
       ticks: '',
       showticklabels: false     
  } 
};

Plotly.newPlot('graph', data, layout, {displayModeBar: false});

function createData(){
var data = [
  [
    0.4, 
    0.4, 
    0.7, 
    -1.0, 
    -0.1, 
    0.6, 
    -0.4, 
    0.6, 
    -0.4, 
    1.3, 
    0.7, 
    -0.4, 
    1.1, 
    1.3, 
    0.6, 
    0.1, 
    -0.0, 
    -0.8, 
    -0.8, 
    -1.0
  ], 
  [
    0.4, 
    -0.4, 
    0.4, 
    -1.2, 
    -0.7, 
    0.4, 
    -0.9, 
    0.5, 
    -0.9, 
    1.2, 
    0.5, 
    -1.0, 
    1.3, 
    1.1, 
    0.5, 
    -0.0, 
    -0.1, 
    -1.2, 
    -1.0, 
    -0.9
  ], 
  [
    0.7, 
    0.4, 
    0.1, 
    -1.2, 
    -0.2, 
    0.5, 
    -0.6, 
    0.6, 
    -0.2, 
    0.9, 
    0.6, 
    -0.5, 
    1.1, 
    0.8, 
    0.6, 
    0.1, 
    -0.4, 
    -0.9, 
    -0.7, 
    -0.8
  ], 
  [
    -1.0, 
    -1.2, 
    -1.2, 
    -4.4, 
    -1.9, 
    -0.8, 
    -2.2, 
    -1.0, 
    -2.2, 
    0.0, 
    -0.3, 
    -2.0, 
    -0.2, 
    0.2, 
    -0.8, 
    -1.6, 
    -1.9, 
    -2.4, 
    -2.3, 
    -2.6
  ], 
  [
    -0.1, 
    -0.7, 
    -0.2, 
    -1.9, 
    -2.0, 
    -0.5, 
    -1.9, 
    -0.3, 
    -1.7, 
    0.4, 
    -0.2, 
    -1.9, 
    0.3, 
    0.4, 
    -0.3, 
    -0.8, 
    -0.9, 
    -2.1, 
    -1.8, 
    -2.0
  ], 
  [
    0.6, 
    0.4, 
    0.5, 
    -0.8, 
    -0.5, 
    -0.1, 
    -0.8, 
    0.6, 
    -0.5, 
    1.0, 
    0.5, 
    -0.7, 
    0.8, 
    1.0, 
    0.5, 
    0.1, 
    -0.3, 
    -0.9, 
    -0.7, 
    -1.1
  ], 
  [
    -0.4, 
    -0.9, 
    -0.6, 
...